Last year, after a slow start, he experienced a career-best midseason run of success and finished 10-8 with a career-best 4.33 ERA.
However, in his final four starts -- three of which came when the team was mathematically alive for a playoff berth -- he went 1-3 with a 9.56 ERA, and yielded a .432 batting average. During that time it was announced that he had "extreme dead arm" -- a general weakness and soreness not necessarily associated with injury -- not to mention a sinus infection.
Well, that isn't the whole story. It all begins with some frightening family history. Hammel discovered before the season that he had a condition most don't expect to see in a fit, 6-foot-6, 215-pound professional athlete.
"A lot of people didn't know this, but I have a family history of heart disease," said Hammel, whose father, William Hammel III, died of a heart attack three days after Christmas 1999, at the young age of 46. "When we did some testing last spring, it showed that I had very high cholesterol."
To manage his cholesterol, Hammel began taking the prescription drug Crestor in April.
Hammel went 0-2 with a 9.16 ERA in April before sustaining a right groin strain and missing 19 days. But from his return on May 15 through Sept. 9, he went 10-5 with a 3.71 ERA. That span included some career-best runs -- a 28 1/3-inning scoreless streak in June, and a six-decision win streak with a 2.17 ERA in nine starts from late May to early July.
By the latter part of the season, however, his effectiveness had disappeared. The velocity on his pitches was the same, but he couldn't put them where he wanted, and even throwing bullpen sessions between starts was a chore. But Hammel believes the underlying reason is the medication.
"One of the side effects is that you feel more soreness," he said. "I'd started taking it in April, and it's a daily medication, so it took a while for it to kick in. It's not an excuse, because I wasn't pitching well, as we all know. But the end of the year, my body wasn't feeling right."
According to Crestor's website, the drug blocks an enzyme in the liver and therefore reduces LDL (bad) cholesterol. The drug, with diet and exercise, can reduce the buildup of plaque in the arteries.
However, muscle pain is a side effect. In fact, a warning says that "unexplained muscle pain, tenderness or weakness, especially with fever" should invoke a call to a doctor, since it could be an early sign of "a rare muscle problem that could lead to serious kidney problems."
Of course, soreness comes with merely pitching a Major League game, so an increase in the soreness was enough to move Hammel to develop a new strategy.
"I weaned myself off that," he said. "My wife has received acupuncture. I didn't know needles could help with the cholesterol, but with the help of my wife, we talked to a doctor and started doing that. I've also begun taking some natural, herbal medicines that do the same thing Crestor does, but it's not as processed or chemical.
"I also made some changes to my diet and workout regimen. My body feels great. I know managing my cholesterol is a serious life matter, but I also want to be able to do what I do."
One of the Rockies' priorities this winter is to build starting pitching depth. They traded infielder Clint Barmes to the Astros for right-hander Felipe Paulino, an intriguing power arm who had pitched more out of the rotation than the bullpen in his career. Former Dodgers lefty Eric Stults will be in camp as a non-roster invitee. Right-hander Esmil Rogers was better as a reliever than as a starter last year in the first extended big league action of his career. All this could be seen as a challenge to Hammel's standing in the rotation.
But the Rockies, after monitoring Hammel's health closely and conducting a physical this week, signed him to a contract that shows they expect him to be a key part of the immediate future.
"It's nice to have them show faith in me," Hammel said. "Even though I did falter at the end of last year, I've seen improvement. I could have folded up the ship after April, when I started off terrible. I can't take all the credit or blame for wins and losses, but after that I did my part to keep the team in games, and showed that I wasn't a fluke.
"This contract doesn't mean anything is being given to me, but it says I'm in their plans for the next two years, maybe beyond. Now it's up to me to go out and produce for a full year. I feel like the best is yet to come."