Close your eyes (unless you're driving, in which case quit reading baseball articles on your phone when you're driving, and also don't close your eyes). Picture the prototypical home run basher.
Sure, the microscopic Jose Altuve was still capable of 24 of them last time, but who you are picturing is likely quite different from a 5'5" second baseman. If you are a St. Louis Cardinals fan beneath a certain age, you may be thinking of Albert Pujols (if you don't remember Albert Pujols, that's fine, but please, I'm trying not to feel too old here), but if you are old enough to remember the 1990s, the name Mark McGwire should come to mind immediately.
McGwire, of course, sailed past the MLB single season home run record with his 70 dingers in 1998, and for good measure, he broke the old record of Roger Maris again in 1999. Particularly due to his penchant for 500-plus foot blasts, his power was an aesthetically pleasing alternative to the quick-footed 1980s Cardinals of Vince Coleman, Willie McGee, and Smiths Lonnie and Ozzie.
But McGwire was a good player beyond his sheer power; sure, his power was what made him great, but he wasn't unskilled in other departments. While his fielding had diminished by his age-34 season of 1998, he was an above average defensive first baseman in his younger days.
Most important for his Cardinals tenure was his excellent eye: while McGwire did benefit from more than his fair share of intentional walks, arguably to the point of irrationality (this phenomenon became even more famous with Barry Bonds before the folly of giving a free base to "the guy you can't let beat you" became more apparent and the IBB became a more selective strategy), his 23.8% and 17.2% walk rates for 1998 and his career, respectively, were not merely the byproducts of scared pitchers. McGwire had a 205 wRC+ in 1998 while Sammy Sosa, with just four fewer home runs, managed "just" a 159 with his much more pedestrian 10.1% walk rate.
In 2016, no player in baseball better epitomized the slugger archetype than Mark Trumbo. The 6'4", 235 pound 30 year-old hit 47 home runs, the most in baseball, while alternating mostly between right field and designated hitter for the Baltimore Orioles, although Trumbo has also played first base. And if the Cardinals could conceivably make a run at Edwin Encarnacion, there would seemingly be reason to believe that Mark Trumbo would be a similar type of player. And likely at a lower cost—while MLB Trade Rumors predicted Encarnacion would garner a four-year, $92 million contract, they project Trumbo at four years and $60 million.
In a past era, Trumbo would be considered one of free agency's biggest names. However, his 47 home runs are the result of the only major attribute he has. Trumbo strikes out a lot, which in and of itself is forgivable, but he walked just 7.6% of the time. He is a non-factor on the basepaths, stealing two bases in 2016 and being a below-average base runner by Baserunning Runs in all six of his full MLB seasons.
Unsurprisingly, given his lack of mobility, he is a poor fielder, and while this problem would be somewhat mitigated by playing him at first base rather than the outfield (he has been a somewhat above average defensive first baseman during his career), Trumbo has not been a full-time first baseman since 2013, and with an additional four years of aging, it is hard to imagine that he would be much better than passable at the position.
Of course, signing a defensive liability is fine if he can make up for his fielding deficiencies at the plate: 2001-2004 Barry Bonds was a shadow of his former defensive self but he was such a prodigious hitter that nobody complained. But in Trumbo, some team will be signing a player whose 2016 wRC+ was 123 and whose Wins Above Replacement was 2.2 by FanGraphs and 1.6 by Baseball Reference; the WAR totals suggest that Trumbo was somewhere around league average in his supposed breakthrough season. Although he had flashier stats to back it up, Trumbo's wRC+ was nine points lower than that of Aledmys Diaz. A good hitter, sure, but not the kind of player who, when devoid of any real defensive value, is worth paying a ton of money.
There is a reason Trumbo declined Baltimore's $17.2 million qualifying offer, despite being worth barely that much in his career year of 2016: 47 home runs looks eye-popping. Even sabermetrically savvy front offices will be tempted, but Trumbo marks a huge risk, particularly on a multi-year deal.
The signing of Mike Leake was questioned by many, including myself, but if nothing else, the worst case scenario was that the Cardinals would have a slightly below league-average starter capable of his share of innings, which itself has value (his upside was arguably too low to justify $16 million per year for half a decade, but that's a different matter).
The signing of Dexter Fowler also may not pay off, as he is seemingly a buy-high candidate, but while his pre-breakthrough performance may not be elite and may result in him moving to a corner outfield position sooner than desired, the contract would not be a complete black hole if he became the kind of player in his thirties that would have been expected before 2015.
However, if the Cardinals were to pursue Mark Trumbo, not only is the upside, if 2016 is his power peak, probably somewhere around what he will actually get paid, but the downside could be catastrophic, as he would need to maintain well above average offensive performance to justify the defensive dip that would come from the corresponding move of switching Matt Carpenter back to third base. Unless Trumbo’s market completely bottoms out, the risk simply is not worth the probably minimal reward.