On many an August or September night, he'd look at the center-field scoreboard at Fenway Park, where velocity is tracked and see 90, 91 or 92 mph. Did Delcarmen need to get his eyes checked? Was the radar gun broken?
The truth is that as much as Delcarmen tried to make himself believe otherwise, he was pitching through right shoulder fatigue that he didn't tell the team about until it was too late.
The injury turned out to be minor and probably could have been avoided altogether if he had just told manager Terry Francona he needed a few days off.
"They told me they thought it was just a little tendinitis or something," Delcarmen said Thursday. "I don't know, because I had never had any shoulder problems before, but maybe I was a little fatigued and that caused a little tendinitis. Like I said, it's a lesson learned. I'll try to stay strong all year and not be in that position."
Why didn't he tell anyone?
"I just feel as a pitcher, I've felt bumps and bruises before that, and I felt like I could muscle through," Delcarmen said. "I just kept telling myself over and over to try to get through it, and it just kept getting worse and I couldn't really take it anymore."
If there was a rock bottom, it was probably when the righty got in a car accident the weekend before the postseason, causing pain in his back and neck. He was left off the American League Division Series roster and watched as the Red Sox were swept in three games by the Angels.
It is over now, and Delcarmen vows to be more open with the training and coaching staffs this year.
"The thing is, Tito even said he loves guys who just want to go out there and compete. But he told me that if I feel something, I should say something," Delcarmen said. "I'd look back and expect to see 95, 96 mph, and it wasn't happening. The last time I threw at Fenway, it was to the point where I just couldn't throw. I keep saying, 'Lesson learned,' but I definitely learned from last year. I feel good; I feel 100 percent ready to go."
But there Delcarmen was on Thursday, throwing batting practice to hitters and looking like he always had before the final weeks of last season. In other words, his fastball was exploding, his curveball was bending dramatically and his changeup was perplexing.
"It was pretty good," Delcarmen said. "I felt good. The ball was down in the zone. I couldn't ask for more than that, so I felt good. I feel 100 times better than I did last year toward the end. It's just good that I feel normal and ready to go."
Though he is far from the biggest name in the Boston bullpen -- Jonathan Papelbon, Daniel Bard and Hideki Okajima all get a lot more recognition -- Declarmen can be a vital piece when he is right.
Francona has leaned on Declarmen a lot through the years. Though he is still fairly young at 28 years old, Declarmen is ninth in franchise history with 241 relief appearances. Only nine relievers in the Majors have appeared in more games than the 181 by Delcarmen over the past three seasons.
"He's been a pretty important part of our bullpen, whether he's pitching in the sixth inning or the seventh inning, because he can get left-handers out and because of his ability to throw the changeup," Francona said. "He's got enough power in his breaking ball to get righties out. He's that guy that can throw one-plus innings. We might be down a run or two, but he's that guy that gives us a chance to win. There's a lot of ways he can help."
The only thing that declined more than Delcarmen's fastball in the last two month of 2010? His statistics.
The ERA progression said it all. He was a perfect 0.00 in April, followed by 3.00 in May, 4.00 in June, 4.66 in July, 5.25 in August and a whopping 14.14 in September/October.
"We were running through some problems with Manny for a while. The velocity was ticking off," Francona said. "He wasn't using his legs as well as he should. I think it's a combination of things. I think when that happens, you start trying to throw harder and not using your legs. He wasn't real open about it. A lot of players are like that. Then, when things go well and you fight through it, you appreciate it. But then when you lose a player, it's tough. So there's a fine line that we recognize."
And the Delcarmen of 2010 should be able to look back at the board and see the 96- and 97-mph readings that he's become accustomed to.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.