|The men in question|
First off: after a stellar start to the season, Marcum finished in the gutter. Over the month of September he went 2-2 and posted a 5.17 ERA. Those numbers look stellar compared to his complete postseason meltdown where he went 0-3 and his ERA was over 14. These numbers are hard to measure out because before they can be taken be taken as conclusive evidence of anything, there are several factors about Marcum that need to be considered.
First, about Marcum, he's a Tommy John pitcher. That's crucial information, because it indicates a lot about a pitcher's durability. It's possible, and moreover logical to assume that Marcum had simply ran out of gas for the season. While I do believe in intangible factors like "clutch" and "closer mentality", I also believe in rhetoric and being bullshitted by players who want to play despite being incapacitated. Marcum is a bulldog of a competitor, and while that's honorable, I'd wish he'd been pitched about 40 innings less before October came around.
Secondly, we aren't even sure how good the Brewers are going to be this year. I'm a lot more optimistic than a lot of the "fans" I've heard whining about how Prince Fielder's end in a Brewer's uniform signals the end of our relevance as a franchise. Assuming our rotation is healthy, it has the potential to be elite. And while Fielder is gone, he has been replaced (sort of) with Aramis Ramirez, who is lesser but still effective. Point being is that with at best a tenuous grasp as to where we'll be come July, the decision to extend a potentially amazing trade piece is a difficult one. How long does the Crew want to hold on to two very good starters if they are suddenly thrust in to the realm of rebuilding?
My guess is that the Brewers are going to be fine, even without Braun. If we are anywhere near contending, Greinke and Marcum will both be here at least until October. If we are .500 or lower, I'd expect to see at least one, more likely both, traded off. An extension for either pitcher would be a HUGE indication for what the franchise wants to do going forward. Grit your teeth Brewers fans, lets hope to see these two happy looking young men in the blue and gold for seasons to come.