Apart from Tarik Skubal, the Tigers' rotation has been entirely too unpredictable this season. Casey Mize and Jack Flaherty, the only other starting pitchers who have been with the team all year, have become two of their biggest wild cards as the Tigers approach the postseason.
Mize's early season success has proven to be more sustainable than Flaherty's, and he's had a better bounce back so far from a 5.81 ERA August. Flaherty posted a 5.51 ERA last month and hasn't recovered quite as well through two starts in September.
The real difference is that Mize seems to have found more of a plateau, while Flaherty has very high highs and very low lows.