Marcell Ozuna’s first few months as a St. Louis Cardinal were disappointing. He didn’t hit well and he made a few ugly, high-profile defensive lapses which tarnished the reputation that comes with being a defending Gold Glove winner. But particularly in the second half of the season, Ozuna has come around. He has been an above-average hitter over the course of the season, he is well within striking distance of the second-biggest home run season of his career, and despite his lackluster reputation in the field, his Ultimate Zone Rating actually indicates he has been slightly above-average in the field (to be fair, one should not see that and conclude he’s a good fielder, but to be fairer, one should not see above-average numbers and conclude he’s a bad one).

Ozuna was a borderline down-ballot MVP candidate last season, but going by projections, which consider his 2017 breakthrough but also consider the kind of player Ozuna was before last season, Ozuna is going to wind up being, well, basically the kind of player he was expected to be. ZiPS had Marcell Ozuna as a 3.1 Wins Above Replacement player, and while he is probably going to fall just shy of that mark, his season is hardly a disaster.

It’s been a tale of two halves for Ozuna, whose offensive surge has corresponded with the Cardinals as a whole going from middling outsider to Wild Card leader. Inevitably, Ozuna is going to be compared with his former outfield teammates with the Miami Marlins, Giancarlo Stanton and Christian Yelich. By all accounts, the Cardinals tried to acquire Stanton last off-season, but he was unwilling to approve a trade to St. Louis, so comparing Ozuna to Stanton is pretty unfair as it wasn’t as though the Cardinals really had a choice in the matter (and it looks like they would’ve chosen Stanton if they did).

In the case of Christian Yelich, however, the Cardinals could have made that trade. It helped intensify the Marlins’ desire to move him once Ozuna was traded, granted, but Yelich was transparently on the table from the beginning; plus, presumably, if the Cardinals hadn’t acquired Ozuna, somebody would have. And while Marcell Ozuna has had a decent season and a very good second half, Christian Yelich is an MVP candidate for the Milwaukee Brewers. And considering that the Cardinals have been chasing the Brewers throughout September, it’d be pretty nice to have gotten the better Marlins outfielder.

It’s hard to say just how big of a gap there is between Yelich and Ozuna in terms of true talent: we can look at their wRC+ and see that Yelich has a substantial edge, but as of the time I wrote this sentence, Yelich had a 63 point edge by batting average on balls in play. Yelich is faster, so that he has the higher BABIP is expected; Yelich is now, however, a “63 points better by BABIP” level of faster. But by xwOBA, which measures quality of contact and weighs players accordingly, Yelich is still better. His xwOBA is in the top ten in all of baseball; Ozuna’s is 57th.

But the question in the off-season wasn’t so much Yelich vs. Ozuna but rather the degree to which the Cardinals would prefer Yelich. Not only was Christian Yelich the more consistently terrific of the two, but he was a year younger and, more importantly, under a very team-friendly extension–Yelich was guaranteed an average of just over $11 million over the next four seasons with a team option for 2022. Ozuna’s contract situation was team friendly enough–a below-market contract for 2018 in the second year of his arbitration stage with another below-market 2019 season to follow (assuming Ozuna didn’t completely fall off, at which point a team could cut bait by not tendering him a contract, though this was always highly unlikely)–but it wasn’t Yelich-level.

This is what caused the huge difference in cost for the Cardinals for Ozuna and the Brewers for Yelich. The centerpiece of the four prospects traded for Ozuna by the Cardinals was Sandy Alcantara, who has pitched well in his brief MLB stint this season by ERA but continues to exhibit substantial control problems, and was a bit of an afterthought for the Cardinals. Magneuris Sierra, the one-tool outfielder who had zero extra-base hits in 64 plate appearances in St. Louis, has been substantially below replacement level for the Marlins, with his 21 wRC+ and defensive metrics which do not line up with his obvious speed. And Zac Gallen and Daniel Castano haven’t done much of anything in the minors this season. The Cardinals, ignoring the Yelich alternative, probably won the Marcell Ozuna trade because the players they traded have little value to them.

For Yelich, the Brewers sent Lewis Brinson, Jordan Yamamoto, Monte Harrison, and Isan Diaz to Miami. Even with Lewis Brinson being more or less MLB-ready, this was always a win-later move for the Marlins, so to say the Marlins botched the trade this early would be a bit premature. But the prospect loss hurt the Brewers system, even if the addition to Yelich justified it.

John Sickels, SB Nation’s resident prospect guru, ranked Lewis Brinson as the Brewers’ top prospect before the 2017 season, while ranking Isan Diaz fourth and Monte Harrison twentieth (Jordan Yamamoto got an honorable mention). So what are the comparable packages from the Cardinals based on Sickels’s rankings?

• By pulling players based on corresponding rankings, and literally using a random number generator on the honorable mentions by letter grade: Alex Reyes, Harrison Bader, Zac Gallen, Nick Plummer.
• By choosing a player based on letter grade comparable to the Brewers traded: Luke Weaver, Carson Kelly, Randy Arozarena, Daniel Poncedeleon
• By picking comparable players by grade and positionality (probably the most accurate representation of what a trade might have taken): Harrison Bader, Delvin Perez, Dylan Carlson, Ronnie Williams

Let’s consider the latter trade, which probably includes a slightly lighter trade package than what the Brewers actually sent (the Cardinals didn’t have an outfield prospect of Brinson’s acclaim, so I gave the proposal a bump with Carlson instead of Harrison). Would you make that trade? You probably should–as much as Bader has been a revelation this season, he hasn’t been an MVP-caliber outfielder like Yelich has. But would you trade Bader and Ozuna for Yelich? It becomes trickier to answer. The answer might still be yes, but it does expose that trading for Christian Yelich would’ve required dipping into depth which has proven very valuable for the Cardinals in 2018.

The Marcell Ozuna trade is shaping up to be one of the great coups for the Mozeliak/Girsch administration–the Cardinals got a really solid outfielder for two years for what, for all intents and purposes, for their sake, should amount to nothing. Perhaps the Cardinals overrate and over-hoard their prospects, but that doesn’t mean that low-risk, high-reward moves like the Marcell Ozuna trade shouldn’t happen.