The Tigers had a tremendous core of top position players in 2012 with lead-off man Austin Jackson and sluggers Miguel Cabrera and Prince Fielder. They also had one of the strongest overall pitching staffs in baseball, yet they just barely squeaked into the playoffs with a modest 88-win season. The reason was because the supporting cast was very weak.
The Tigers were horrendous at three positions in particular last year - second base, right field and designated hitter. Using FanGraphs WAR as a reference, they were below replacement level at three different positions:
Second Base -1.5
Right Field -2.0
Designated Hitter -0.8
The main culprits at second base were Ryan Raburn, Ramon Santiago and Brandon Inge. They were saved somewhat by the mid-season acquisition of Omar Infante (+0.8 WAR). Brennan Boesch, Don Kelly and again Raburn hurt them in right field. The biggest drag to their WAR at DH was Delmon Young.
They now have new players at each of those positions - Infante at second, a hopefully healthy Victor Martinez at designated hitter and now Torii Hunter in right field. Neither move has the emotional impact of the Cabrera trade or the Fielder signing, but they should be substantial upgrades in terms of wins.
Infante averaged 2.8 WAR from 2010-2012. I'll knock him down to 2.0 WAR because the American League is generally a tougher league (except in the World Series apparently) and he'll be 31 years old. That's a 3.5 WAR improvement at second base.
The newly acquired Hunter has averaged 3.9 WAR over the last three years. Let's take him back to 3.0 given that he is 37. That still comes to a 5.0 WAR improvement over last year in right field.
Finally, Martinez will return after missing a season with a knee injury and be the primary designated hitter. Martinez averaged 3.6 WAR between 2009-2011. Because he is coming off a serious injury, I'm going to cut his WAR almost in half to 2.0. That still amounts to a 2.8 WAR improvement.
So, given what I think are fairly conservative estimates of the values of Infante, Hunter and Boesch in 2013, the Tigers appear to have added 11 wins at the three positions combined. That's a lot of wins, but it shows the importance of having good complementary pieces for their fantastic core.
Does this mean I'm predicting 99 wins for the Tigers next year? No, I'm not making a prediction yet. When I do, I always assume regressions from great players and leave room for injuries, especially to pitchers. I probably won't guess 99 without another substantial acquisition or two. I will say though that they are in much better position today than they were on opening day 2012.