He is now 0-9 with a 5.76 ERA this season. He's allowed 11 runs in his last two starts. However, while he is 0-7 with a 6.34 ERA in 49 2/3 innings over nine starts this season, he is 0-2 with a 2.79 ERA in 9 2/3 innings during two relief appearances.
The Mets are 2-10 in games Marcum has appeared in this season.
Terry Collins said after Wednesday's game that he intends to stick with a six-man rotation between now and the All-Star break.
Marcum as he has yet to win a decision and his ERA is the worst among Mets starters. This is definitely a reasonable justification for removing him, but there are other considerations as well. A variety of advanced stats overwhelmingly suggest he's been the victim of bad luck, which is very likely to balance out over time. Strike out rates and batted ball types are all in line with his career numbers, which strongly suggest he's performing at a similar level. His walk rate has even gone down this year. So, while it's tempting to make this decision based on the last two months, the most important question is: who will pitch best over the next two months?
There's also the issue of trade value. Many contenders will find themselves in need of a fifth starter who can strike out a lot of batters and keep the ball in the ballpark. Moving Marcum out of the rotation likely hurts his trade value. If the team hopes to get something out of him that could contribute beyond this year, their best bet may be to gamble on his numbers improving over his next few starts, rather than stick him in the bullpen and consider him a loss.
I agree that Marcum has dealt with a lot of tough luck and mostly poor run support this season. It's also worth mentioning he had virtually no Spring Training and very few innings while he was rehabbing from his neck and arm injuries at the beginning of the season. It was clear he was still building himself up during his first few starts. But, when it comes to deciding who stays or goes from the rotation, I get the sense it will come down to who has a greater ability to succeed in the assignment. Yes, Marcum has shown an ability in a small sample that he can pitch in relief, but he doesn't have the track record to support the case. I still think Jeremy Hefner remains the best fit to come out of the rotation and go to the bullpen when the Mets revert to the five-man rotation next month.