It’s an oxymoron, the unreliable workhorse. Maybe it doesn’t make sense. But Bartolo Colon has thrown over 340 innings over the past two years, and that’s 62nd in the league. Seen in total, the results have been great — his ERA was sixth-best among qualified starters over the last two years. Using available research on the cost of a win, the deal — two years and $20 million — looks like a good one for the Mets.

And yet the risk markers are large.

Some risk comes from the change in park. Over the last two years, Colon has given up fewer home runs per fly ball than the league average. In terms of homer-suppression, the Coliseum was fifth-friendliest in baseball to pitchers. Citi Field was 11th-friendliest to hitters, as it slightly augmented home runs in general. Over his 16-year, career, Colon has given up more than a homer per nine innings in 12 seasons. Over his last two seasons in Oakland, he didn’t hit that benchmark. There’s a chance he gives up more long balls in New York.

One piece of risk comes just from his age. At 41 this year, Colon is off the far end of the aging curve map, in uncharted territory when it comes to starting pitching. Since 1974, only 24 pitchers have qualified for the ERA title over the age of 40. Three threw the knuckler primarily and one threw the spitball.

The age goes hand in hand with the injury risk. Bartolo Colon is the starting pitcher most likely to head to the disabled list next year in Jeff Zimmerman’s starting pitcher DL projections. Those are based on age and past trips to the DL. Since Colon has gone on the DL for thigh, abdomen and groin issues over the last three years, he hits the disabled list in two-thirds of this year’s simulated seasons. Maybe it won’t be an arm issue, maybe it will.

Durability is obviously a component of this injury risk. Colon’s velocity and effectiveness dwindled as the season went on in 2013, to the point where he was passed up for playoff starts when the games mattered most. Sometimes his velocity perks up again when after he hits the DL for a refresher, sometimes it doesn’t:

The erratic nature of his fastball velocity is a little scary, especially when wrapped up with the injury risk. Consider the four starts that led into his disabled list stint last season. As he lost more than a mile per hour off his average fastball velocity in successive starts, his effectiveness plummeted. He struck out eight, walked nine, and gave up 13 runs and two homers in the 18.2 innings leading into his two-week vacation.

There are a few risk factors that skew positive for Colon. He throws strikes, for one, and pitchers with good command have traditionally aged well. Perhaps it’s merely a proxy for good mechanics, but it seems to be working for Colon recently. He throws mostly fastballs, for two. He leads the league in fastball percentage, actually. Staying away from heavy breaking ball usage is good for your health.

And you have to look at this deal in the context of the league as it stands now. Dan Haren is only 33 and has thrown about as many innings as Colon over the last two years, and he only got one year and $10 million. Perhaps the hip and back problems that made Anaheim so nervous are obvious to any signing team. Scott Feldman got three and thirty, but he’s only just now turning 31 and was injured two years ago. He got the extra year because he’s younger. Tim Hudson has a lot of things in common with Colon, at 39 and coming off an injury, and he got $3 million more than the new Met. Scott Kazmir has a lengthier injury history, but is younger, so he got $2 million more.

Each of Bartolo Colon‘s risk factors comes with an asterisk. Yes, he’s moving to a park that gives up more homers. He’s also going to the easier league for a pitcher. Yes, old pitchers get injured more often. He’s a strike-thrower that doesn’t rely on elbow-stressing breaking pitches. And among the old-pitcher co-hort, his stats and arsenal look a little bit like Greg Maddux’s at the same age. Yes, his fastball is rapidly losing gas. He’s been effective around 90 mph before.

So the Mets got an older pitcher for fewer dollars or fewer years than comparable pitchers on the free agent market. And he’s a reliable risk. Or a firm flyer. Or a predictable plunge. Or a steadfast speculation.

Or maybe a cheap, old pitcher.