On the morning of July 22, the Tigers were one game up in the AL Central. They had been in first place at other times during the year, but had either relinquished possession or fell into a tie with Cleveland rather than hold on to it. This time was different, though, as the Tigers built on that lead, and now, a month-and-a-half later, sit 11-1/2 games up on second place in the AL Central and are riding a 10-game winning streak.
The roster had some slight changes to it in between -- Charlie Furbush was replaced by Doug Fister in a deal with the Mariners, and Wilson Betemit had just been acquired to fill the Brandon Inge-sized hole at third base last time we checked in -- but it's in essence the same team that looked like a .500 club through the first few months of the season.
The results have been dramatically different, though. From opening day through July 21, the Tigers had scored 438 runs and allowed 449 to score, a run differential of -11. With that difference, you would expect a team to be at or around .500, and Detroit was 52-46, not too far off from that pace. Since then, though, the Tigers have scored 268 runs while allowing just 201 to score, meaning the entirety of their now +56 run differential has come since July 22. Their expected record (79-68) based on runs scored and allowed still isn't that hot, but they have played like a very different team since the middle of the summer.
The offense was never to blame for the team's inability to stay in first place. Prior to July 22, these Tigers were fourth in the American League and in the majors in True Average (TAv). They still rank fourth, thanks to hitting .297/.351/.454 as a unit since they gained sole possession of first, a line well above the AL's average of .257/.322/.406, and have also increased their runs per game from 4.6 to 4.8.
There has been just as much of a swing in the other direction for preventing runs. The Tigers' staff allowed 4.58 runs per game through July 21, but since then, have cut that down to 4.42 per game, thanks to a team-wide run average of 4.10 in their last 49 contests. After coming up nearly even in runs scored and runs allowed in the first half, they have been outscoring their opponents by about 0.7 runs per game since. It's not dominant by any stretch, but it's enough to make you win many more than you lose, as the Tigers have done.
The starting pitching has been about the same, with one major exception: Justin Verlander continues to anchor the staff and is making a case to be the league's MVP, while Max Scherzer has been inconsistent but generally productive. Rick Porcello allowed a 942 OPS in August, though, and Brad Penny has continued his quest to strike no one out and be generally terrible despite pitching in a park that favors hurlers.
Those last two are the reason why adding Fister -- the one exception -- has been important. [Edit: This is what happens when you have too many tabs open -- Fister is 5-1 in his eight starts with the Tigers. Luckily, the Mariners' offense, is, in fact, still bad.] While Fister himself is just 1-2 with Detroit, the team is 6-2 in his starts. He is averaging over 6-1/3 innings per start with the Tigers, has an ERA of 2.28, and a K/BB ratio of 8.2 that is higher than his strikeout rate (7.2) thanks to superb control. Clearly, the Tigers are just trying to make their new pitcher feel welcome in his new home by not scoring any runs for him, making this environment familiar, like the one he's used to thanks to his time in Seattle. Once he leaves, the Tigers' bats wake up, as evidenced by the disparity between Fister's and Detroit's win totals in his starts.
The bullpen has also had a turnaround, as, after allowing opponents to hit .262/.358/.393 through July 21, they have improved to a paltry .219/.302/.330 line. The timing was perfect, too, especially with Porcello's struggles. The bullpen's second-half performance has helped the Tigers win far more one-run games: through July 21, they were 10-10 in those contests, but are now 26-15 on the season. Phil Coke, formerly in the rotation, has a 3.68 ERA and 10.6 strikeouts per nine in his last 22 innings of relief. Joaquin Benoit has allowed three runs since July 22, and is pitching like the guy the Tigers hoped they were signing this past off-season. Jose Valverde hasn't been impressive from a peripherals' standpoint, but he has gotten the job done for Detroit in the ninth this year, with 18 saves and one loss in his last 22 games to go with a 1.25 ERA.
The Tigers are not so dangerous that this 10-game winning streak should put the fear of Jobu into their potential playoff opponents -- they are good, but everyone in the playoffs will be -- but, since late July, they have finally played like this roster should, and rightfully sit high atop the AL Central because of it.