The Cy Young award this year seems to be split in the AL between these two - one with many wins, one with killer stats. But what if they each started for the other team?
Taking the 2010 game logs for Felix and CC one can see game by game results and play 'what if'. We cannot factor in defense too easily, so I'll go with what we got.
Method 1: Put starts together with Yankee runs scored vs Seattle runs allowed (and vice-versa) to see their teams record if the other guy started and the other guys bullpen relieved. Stats are W-L-Tied
Felix: 19-9-2 vs real life 15-15
CC: 12-17-1 vs real life 21-9
This suggests that there would've been almost no difference to the Yankees if they had Felix and the Seattle bullpen pitch instead of CC and the Yankee one.
However, for Seattle it would've been at least a 2 game drop to use CC/Yankees pen instead of Felix/Seattle pen.
Method 2: Use runs allowed by starters mixed with how the other guys bullpen did (ie: if Yankee pen allowed 1 run in CC's 3rd start and Seattles allowed 3 in Felix's 3rd then remove 2 runs from the total that day for Felix and add them to CC's).
Felix: 21-6-3 which is 3 ties instead of losses for the Yankees
CC: 11-16-3 which is 1 more loss and wins changed into ties for Seattle
These methods scream that Felix Hernandez has had a better year and, if provided with the Yankee bullpen, would have as good or better a record than CC Sabathia. Switch the teams these two are on and there would be no talk of CC Sabathia having a shot at a Cy Young when the MOST wins he could have is 11 or 12 (odds are fewer due to when runs scored) and that he could have up to 17 losses (fewer I'm certain as Seattle's pen has given up runs in 14 of 30 starts vs just 5 of 30 for the Yankee pen and CC).
As an extra: it is worth noting that 16 paired starts have Felix throwing as many innings and allowing the same or fewer runs than CC, while 11 times CC did the same vs Felix. They threw the same innings/runs once, while twice Felix went one more inning while allowing one more run.
Of course, the hidden factor is that Felix faced the AL West more, while CC had to face the Red Sox, Rays, and Jays more often. But some of that is balanced by Felix facing the Yankees 3 times (allowing just 1 run - guess he liked the challenge) vs CC facing Seattle (3 runs over 3 games) and CC getting to pitch against Baltimore. Note that Felix has not faced the Jays or Rays but allowed just 2 runs in his one game against Boston so vs 2 of the beasts he allowed just 3 runs over 33 1/3 IP. Too bad Seattle isn't nuts enough to trade him here!
https://www.battersbox.ca/article.php?story=20100908123639522