One year/$4 million is about as cheap as they make free agent starting pitchers these days, and Marcum is probably the best bargain bin find Mets could land with spring training less than a month away. Though Marcum has had some durability issues over the last few seasons, and his fastball is more or less at Chris Young velocity, he's been decent when healthy. And as Chris McShane noted yesterday, even with trips to the DL, Marcum has averaged 28 starts a season over the last three years.
Regardless of his issues, Marcum is a good sight better than the other free agent pitchers the Mets were reportedly eyeing. Carl Pavano, for instance, who probably took himself off the market when he ruptured his spleen shoveling snow. As someone who's cleared driveways his entire life, I'll say that if you destroy an internal organ while shoveling, you're doing it wrong.
UPDATE: Ken Rosenthal says that Marcum's deal include $4 million in incentives, which are likely based on starts or innings pitched.
Correction on Marcum deal with #Mets. It’s a $4M guarantee with $4M in incentives. Previously reported that incentives were $2M.— Ken Rosenthal (@Ken_Rosenthal) January 25, 2013