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Cliff Lee, 1st half: 8-4, 2.64 ERA
Cliff Lee, 2nd half: 4-5, 3.79 ERA
The excuse for Felix's 13 wins was the Mariners. Playing on the Rangers for half a season gave Cliff no such excuse, and he was worse for the better team. When you get better in the 2nd half you are "performing better under the pressure of a pennant run" or some such. When you perform worse, your first half gets discounted a bit.
The vagaries of humans looking for patterns, I guess.
~G