If the Detroit Tigers end up with Justin Upton for two years and $44.25 million, after which he opts out to become a free agent again, that might end up being the best possible outcome for both parties in the deal. Upton's age-28 and age-29 seasons should be peak offensive years, with 30-homer upside now that he's out of the San Diego Padres' pitcher-friendly home park, and the Tigers, who are loaded with big contracts that run into likely decline years, may get the short-term impact signing they couldn't otherwise get. Of course, it could all go south if Upton doesn't perform as expected, but I'm very bullish on his offensive output in the near term.
The Tigers' incumbent left fielder on Monday morning was probably Anthony Gose, a plus-plus runner who can handle center field but has never figured out how to make enough contact to become a major league regular and whose bat will not profile in left. Gose got off to a good start for the Tigers last year after they acquired him from Toronto for Devon Travis, but returned to his previous level of non-performance after that, hitting .225/.305/.334 from June 1 onward, .222/.317/.343 after the All-Star break -- put the endpoint wherever you like, the start of his 2015 season is the clear outlier. Tyler Collins offers more power and contact but less defensive value, and like Gose is left-handed. Mike Aviles hasn't sniffed a .300 OBP since 2010. It's fair to say Upton is replacing some basket of players in left field that would have added up to around zero value in 2016 and 2017.
Upton, who was worth 4.4 rWAR last year thanks in part to the park adjustment for Petco Park and his best defensive season in left field (slightly above average by UZR and DRS) to date, would be a huge value for the Tigers even if he's right around that range again. Dan Szymborski's ZiPS forecasts him for 3.7 WAR, which seems reasonable if not truly conservative, and I'll take the over on the .481 projected slugging percentage and 58 projected extra-base hits. Moving to a park where the left-center wall is 20 feet closer -- and the whole stadium isn't sitting in the path of the marine layer every summer -- shouldn't hurt Upton, who uses the whole field well but has much more power to pull, in the least.
If Upton already has reached his peak and is "just" a 3.5 win player over the next two years, that's still not a bad outcome for the Tigers and he'd probably still opt out given ongoing inflation in free-agent salaries. This deal could go south for the Tigers if Upton performs worse than he has in any healthy season he's ever had in the majors, and I don't think that's very likely given his age, current skill set and lack of any signs that he's already getting out of his offensive peak (such as loss of bat speed). Team opt-outs are usually net negatives for the club, as they're locking in downside but not upside on the deal, but the probability of that downside with a player as young as Upton -- or Jason Heyward, to pick another such contract -- is relatively low.
The Tigers are probably about an 85-win team on paper at this point, assuming some real progression from Daniel Norris, who regained his lost velocity after the trade to the Tigers in July, but they're hampered by a farm system that is unlikely to produce anyone who'll substantially help the MLB team in 2016. (I'd bet on Michael Fulmer being in the 2017 rotation, however, and being a valuable starter by then.) They'll need to get lucky on a few players already on the roster, like Miguel Cabrera staying healthy and arresting his decline -- by the way, that eight-year, $248 million extension kicks in this season -- or getting 350 better-quality innings from Justin Verlander and Anibal Sanchez combined. Signing Upton puts them in reach of one more playoff berth and potentially a deep run into October before the window on their contention closes even further as the roster keeps getting older and the farm system, used to bolster this club for so long, hits a temporary fallow period.