An unfortunate byproduct of baseball’s lack of especially prohibitive team salary controls is that fans can only act as armchair GMs to so much of an extent. Take the St. Louis Blues–Taylor Hall, a recent recipient of the NHL’s Hart Trophy as the league’s Most Valuable Player, will be a free agent at the end of the season, and while any reasonable Blues fan would acknowledge that Taylor Hall is a great player who they’d enjoy to see on the Blues, the salary cap makes it so that major team restructuring would be necessary to accommodate a free agent as coveted as Hall. But if hockey were baseball, fans could lobby for the Blues to sign Taylor Hall because, well, he’s good and it isn’t your money.

When I say this is a problem, I mean this is in a mostly minor sense, in that I find armchair general management to be fun to do. Fans who note that Bill DeWitt Jr., or whoever the owner of their favorite team is, can afford to spend more money and chooses to not aren’t, by and large, wrong. And in the grand scheme of things, if the worst thing the DeWitt family has to deal with is their customers occasionally yelling at them, that’s not a horrible fate.

In discussing Nolan Arenado, the Colorado Rockies third baseman who is widely rumored to be available on the trade market, it is probably realistic to note that Arenado will make $234 million over the next seven seasons if he so chooses to do so. Realistically, if a team were to take on this thirty-plus million dollar salary obligation, it would almost certainly keep the team from making other moves.

But for the sake of this exercise, let’s ignore this. Let’s take the “it’s not my money” ideology, a perfectly defensible ideology, to its logical extreme. Let’s pretend that the St. Louis Cardinals’ budget is flexible to whichever transactional whims you may have.

On Saturday, Bruce Levine of Chicago’s “670 AM The Score” radio network reported a trade offer that he said to have heard–one in which the Cardinals offered, in exchange for Nolan Arenado, a package of newly-acquired pitching prospect Matthew Liberatore, 2019 National League Rookie of the Year vote-getter Dakota Hudson, two-time All-Star starting pitcher Carlos Martinez, and Tyler O’Neill, a 24 year-old outfielder with an above-average batting line and strong defensive metrics during sporadic MLB playing time.

The long-term arguments against this trade are plentiful. Matthew Liberatore is the #41 prospect in all of baseball and is just twenty years old. Dakota Hudson will spend two more seasons making the league minimum and then three more seasons in salary arbitration. Carlos Martinez, especially if he can regain the form of his seasons as the team’s de facto ace, could be a relative bargain at $11.7 million per season, and the team options for 2022 and 2023 are particularly valuable if he takes another step forward. Tyler O’Neill is a former Top 100 prospect who has played well when healthy at the big league level and he provides depth in an outfield situation that has become increasingly thin (for mostly self-inflicted reasons) over the last few months. And while Nolan Arenado is under contract for seven years, he can opt out after two. All parties involved would prefer that he would–Arenado, so that he can make more money in the long term, and the Cardinals, because that would mean Arenado played well enough in his first two seasons in order to make that money.

But let’s look strictly at 2020. I tend to be a long-term thinker when it comes to my preferences in transactions, and that is not necessarily a strength–I probably overdo it. There are other fans who seem to be working under the assumption that Major League Baseball won’t exist beyond next season and/or they will cease to be fans of the St. Louis Cardinals because, I don’t know, they just start liking other things instead and don’t care how future generations of fans feel? But I digress. Let’s pull the trigger on this trade.

Nolan Arenado projects, according to Steamer, the most comprehensive and well-regarded projection system on the market which currently has projections for every MLB team, to be the fifth-best third baseman in baseball. On one hand, this ranking (which matches his ranking among third basemen in 2019 by both FanGraphs and Baseball Reference Wins Above Replacement) stands in contrast to notions of him being a top-five player in the sport, but on the other hand, this makes him a relatively substantial upgrade over the Cardinals’ incumbent third baseman, Matt Carpenter. While Carpenter was a top-ten MVP vote recipient as recently as 2018, during which he was also a superior hitter to Arenado by wRC+, Carpenter projects by Steamer WAR to be a below-average starting third baseman in the sport, ranking 20th. By this metric, Arenado represents a 2.9 win upgrade at third base–4.9 WAR to 2.0 WAR. And since this trade doesn’t include Matt Carpenter, for the time being (and if we are assuming the Cardinals aren’t merely looking to shed salary, or at least shouldn’t be), he can be penciled in as an elite bench bat. While Matt Carpenter isn’t the best third baseman in baseball, he would almost certainly be the best backup third baseman in baseball. The added presence of Tommy Edman arguably diminishes Carpenter’s marginal bench value, but it’s hard to argue that more isn’t better.

While Matthew Liberatore is a major prospect, he probably won’t have much impact at the MLB level in 2020. Highly regarded as he is, Liberatore hasn’t pitched above A-ball and will be twenty years old throughout the entirety of the 2020 season. For the sake of this discussion, he is essentially irrelevant. But the other two pitchers hypothetically being sent to Colorado very much do matter–Dakota Hudson and Carlos Martinez. Hudson overperformed his fielding-independent ERA by 1.58 runs and as such, many analytically-inclined observers expect the relatively low-strikeout pitcher to regress in 2020. Steamer projects Hudson for 1.5 WAR. The system is projecting Martinez for a 0.8 WAR season in a season split between the starting rotation and the bullpen.

But by all means, Martinez is going to be given every chance to start, so let’s double his innings (from 78 to 156) and therefore his WAR. Maybe this seems extremely, but this would entail Martinez throwing easily fewer innings than he did in any of his three full seasons in the Cardinals rotation. So let’s say these two represent 3.1 WAR. But saying the Cardinals would lose 3.1 WAR and that’s higher than the 2.9 WAR of Arenado upgrade is a gross oversimplication, not only because it doesn’t account for Matt Carpenter: Bench Bat, but because the Cardinals aren’t necessarily replacing Hudson and Martinez with Replacement Level-pitchers. Kwang-hyun Kim, the recent free agent signing who was initially labeled a swingman, projects for a 4.32 ERA per RotoWorld, which is acceptable if not remarkable. But following that, the options become increasingly inconsistent. Alex Reyes should be back, but given his injury history, it is no guarantee that he will be as effective as he was four years ago at the MLB level, even if he is able to stay healthy. Austin Gomber and Daniel Ponce de Leon project for ERAs of 4.35 and 4.87, respectively, and Gomber is coming off of an injury-plagued year.

It’s not impossible that a rotation of Jack Flaherty, Miles Mikolas, Adam Wainwright, Kwang-hyun Kim, and one of Gomber or Ponce de Leon could survive, but the risk associated with it is high. You are requiring Adam Wainwright to at least repeat his pretty-good age 37 season at age 38 and not revert back to the version of Wainwright we got at ages 35 and 36. You are requiring Kim to jump from the world’s third-toughest baseball league to the world’s highest competition without missing a beat. And you are requiring perfect health at the most injury-vulnerable position in sports.

Tyler O’Neill is a less established Major Leaguer than Hudson or Martinez, but he plays at an even thinner position. The outfield seemed thin in late 2019 before Marcell Ozuna declined the qualifying offer and before Jose Adolis Garcia, Jose Martinez, and Randy Arozarena were traded. If the Cardinals were to make this trade, the Cardinals would only have four committed outfielders on their 40-man roster, one of whom (Justin Williams) didn’t appear in the Majors last season. The Cardinals’ outfield situation would boil down to Dexter Fowler, who projects to be a below-average offensive outfielder; Harrison Bader, whose offensive shortcomings were so profound that despite having Gold Glove finalist level defense, he was demoted to Memphis during the season; Lane Thomas, who has 44 MLB plate appearances; and Justin Williams, who has one career MLB plate appearance.

Would Nolan Arenado improve the Cardinals next season in a vacuum? Of course. Would Arenado improve the Cardinals if they were giving up this particular package? Under the most generous reading of the situation, let’s say the loss of Hudson and Martinez combine for 1.5 fewer wins (I think this is underselling it, but since we’re dealing with fickle projections, I’m willing to be a bit conservative on the matter). O’Neill projects for 0.7 WAR, and while I’m relatively inclined to just subtract that raw total given the dearth of outfielders on the Cardinals, let’s cut it down to 0.5 WAR. Let’s assume Liberatore is worth nothing to the 2020 team (this is by far the safest bet). This 2.0 WAR deficit is overcome by the 2.9 WAR Arenado improvement. A 0.9 WAR bump may not be franchise altering and it may not make the Cardinals runaway NL Central favorites, but it’s still certainly a positive.

You know what would be better than a 0.9 WAR bump? A 2.6 WAR bump. Such a bump is available, and such a bump requires far less of a long-term commitment in order to satisfy short-term demands. That bump would come by the Cardinals acquiring Josh Donaldson.

Donaldson, who eclipsed Arenado by Baseball Reference WAR in 2019, projects to be a worse third baseman in 2020 than Arenado, but by a mere 0.3 WAR. Donaldson, who was the 20th best position player in baseball in 2019 by fWAR (eclipsing the fWAR total of any St. Louis Cardinals player, including pitcher Jack Flaherty), projects for 4.6 fWAR by Steamer, making him the 19th best position player for 2020 (Arenado ranks 14th). Over the last half-decade, Donaldson has been the superior player, and while Donaldson’s inferior fielding (note: Donaldson is still an above-average defensive third baseman and has been above-average by Ultimate Zone Rating in all eight seasons of his career at the position) has made him a recently less valuable player than Arenado, Josh Donaldson was a superior hitter by wRC+ in 2019. Donaldson is also very impressive by back-of-the-baseball-card numbers: he hit 37 home runs and was ten total runs away from scoring and driving in 100 runs.

But most importantly, Josh Donaldson is free. Well, not “free”–the Cardinals would have to give him a bunch of money. But if we’re willing to ignore the financial considerations of giving Arenado $30 million-plus, we should certainly ignore the considerations of Donaldson’s contract, which would certainly be shorter and certainly have a lower average annual salary. And unlike Arenado, who would reportedly come at a substantial prospect and MLB-ready talent cost, adding Josh Donaldson wouldn’t cost the Cardinals their pitching depth nor what is left of their outfield depth.

The most baffling part of Nolan Arenado trade rumor season is that Anthony Rendon, who has been demonstrably better by the metrics over the last few seasons and projects to be better going forward, was a free agent a month ago and the Cardinals were never seriously rumored to be interested in signing him. But even if you want to assume the Cardinals suddenly had an epiphany following Rendon’s signing during which they assumed that Matt Carpenter was so conclusively cooked that they must invest in a new third baseman, not simply signing Josh Donaldson doesn’t make sense. By signing Donaldson (and, in turn, depriving playoff competition, namely the Milwaukee Brewers, from signing him), the Cardinals would cement themselves as NL Central favorites and, since Donaldson is 34 years old, be able to do so with limited long-term downside given the shorter term to which he can be inked. If the Cardinals traded the rumored package for Nolan Arenado, they would arguably be worse in 2020 than they were before the trade.

I stand by my belief that a trade as rumored presently would not happen because it requires a belief in the incompetence of the Cardinals’ front office that I simply do not have. Selling low on Carlos Martinez and Tyler O’Neill in order to obtain a market-level contract in Nolan Arenado’s in lieu of signing one of the best third basemen in baseball would be the most demonstratively lopsided trade in St. Louis Cardinals history, and one of the most baffling, immediately regrettable transactions in recent memory. The Wasserman agency, which represents Nolan Arenado, is one of the most widely-respected sports agencies across all four major North American professional sports, and they strive to squeeze every penny for their clients; to assume that, one year after signing his life-altering extension, Nolan Arenado is so underpaid that he could demand this package requires such a lack of faith in Wasserman that the organization should cease to exist. And if a baseball team is willing to give up more than peripheral pieces in order to obtain Nolan Arenado, the metrics which evaluate players are clearly astonishingly different between the private sector and the public sector, which, broadcaster puff pieces aside, pins Nolan Arenado as a good but not elite player.

Cardinals fans are demanding a Nolan Arenado trade, but if this trade were to happen, it would (likely) be a disaster, and those fans are not going to forgive Michael Girsch and John Mozeliak for creating such an unnecessary albatross. It is their job to act rationally, and trading such an astonishing package for Nolan Arenado rather than signing Josh Donaldson is irrational beyond precedent. This would be a trade that would devastate the Cardinals organization for the next decade, based on a blind notion that “the Cardinals just need a big bat in the middle of the order”, a phrase that has been uttered in each of the prior two off-seasons. But if the Cardinals truly were only one big bat at third base away from becoming legitimate World Series contenders, the biggest bat available is Josh Donaldson.