The Tigers trudged through the first five months of the season with no guarantee of a playoff berth, after they simply couldn't jump past the White Sox in the AL Central. Finally, they made their move in September and clinched the division, eventually winning the AL pennant (like many imagined they would) before getting completely shut down in the World Series by the Giants. I'm not sure if this season would be considered a success (because they won the pennant) or a failure (because they nearly didn't make the playoffs and then got embarrassed in the World Series), but things could have gone much differently in either direction for the Tigers.
What Went Right: Miguel Cabrera won the AL Triple Crown, and will either be 1 or 1A in AL MVP voting when the award is announced in two weeks. Justin Verlander followed his 2011 AL MVP season with a year that will likely give him a second straight AL Cy Young award. Austin Jackson had another great year in center field for the Tigers, making the leap to the top tier of center fielders in baseball. Prince Fielder "only" hit 30 homers, but walked more than he struck out with a career-best .313 average behind Cabrera in the Tigers lineup. Max Scherzer stayed largely healthy, and his true talent blossomed, striking out 11 hitters per nine innings in 32 starts. Doug Fister and Rick Porcello were varying degrees of solid for the Tigers, and midseason acquisition Anibal Sanchez was great in his 12 starts as a Tiger. Octavio Dotel was awesome in the pen, so much so that the Tigers picked up his option for the 2013 season.
What Went Wrong: Catcher Alex Avila took a major step in the wrong direction, seeing his power fall completely off a cliff in 2012. Shortstop Jhonny Perlata had his BABIP fall by 50 points and all three of his slash stats fall across the board. Second baseman Omar Infante was a massive improvement for the Tigers after his July acquisition, but wasn't as impactful as expected. The team wasted 1100 plate appearances on Delmon Young and Brennan Boesch, with the pair contributing for -2.0 fWAR…by the same token, Young was a big part of the Tigers winning the ALCS over the Yankees. Ryan Raburn and Ramon Santiago were an absolute disaster at second base until Infante arrived, which is why you might be able to qualify his presence as anything but a disappointment. Detroit's bullpen also had its struggles, with Jose Valverde's ERA jumping by a run and a half and Joaquin Benoit allowing 14 homers, or only five fewer than Verlander did in 160 more innings.
Most Surprising Player: We all knew Max Scherzer was good, but this was the first year where he was truly great. Scherzer struck out 11.08 batters per nine innings and posted a 3.85 strikeout to walk ratio, both of which were far and away career bests. Scherzer still had problems with homers and had a pretty low groundball rate, but with strikeout and walk rates like what Scherzer possessed this year, you can survive.
Most Disappointing Player: I think I'm going to go with Brennan Boesch, and not beacuse I expected him to be some sort of monster for the Tigers this season. Boesch had a 1.7 fWAR season last year, which is fine…it's not great, but it's fine. In 2012, his fWAR fell by three wins while his BABIP fell by just 30 points, his walk rate fell by two full percent, and his strikeout rate jumped by three full percent. Boesch's defense also reverted to its disastrous 2010 level after a solid enough 2011. He didn't even make the playoff roster, losing his spot to 21-year old rookie Avisail Garcia, who ahd just 51 plate appearances in the majors during the regular season. I mean….lord.
Prospects Up: 20-year old third baseman Nick Castellanos beat the cover off of the ball in high-A, but struggled in AA after a midseason promotion. Drew Smyly had a solid year as the team's fifth starter after being drafted in the second round of 2010's draft. Avisail Garcia moved quickly through the system and was on Detroit's playoff roster, despite questionable plate discipline in the minors.
Prospects Down: Jacob Turner struggled all season, and was eventually shipped off to the Marlins as part of the Sanchez/Infante trade along with highly-touted catcher Rob Brantly. Casey Crosby struggled with his control in AAA, and got obliterated in three starts in the majors. Andy Oliver's control was completely lost in AAA.
The Future: Detroit's 2013 season will be very similar to 2012. The team's most significant free agents are Valverde and Sanchez, and both can be replaced in the free agent market this offseason. They still have a hell of a core together, and Victor Martinez will be back next season to hopefully make their offense even more scary after a slightly disappointing output this season.