PHILADELPHIA -- There was a twinge of trepidation when Rockies starter Aaron Cook took the mound in late September after being sidelined for over a month with a strain of his right shoulder.
"Initially, yeah, there was a little bit," Cook said. "Because missing a month to six weeks, you just never know how you're going to rebound."
Now Cook will be charged with helping the Rockies forge a tie in the series, after the Phillies ran off with a 5-1 victory in Game 1 of the National League Division Series on Wednesday.
The Rockies certainly feel they have the right guy on the mound who can do that in Cook, who carried them in 2008 and might have been on his way to another big season had he not missed a month of action.
In his first two games after coming off the disabled list on Sept. 25, Cook threw five shutout innings in a victory over the Cardinals and followed it up with a gem against the Brewers on Oct. 1 -- the game in which the Rockies clinched the Wild Card berth.
Cook allowed one run over eight innings in the victory over the Brewers.
Righties and lefties are each batting over .280 against him this year
Rockies pounded him this season
His sinker must be on
The guy is clutch
"I think the first game I had a little bit of rust, walked a few guys," Cook said. "But after I got past that, I knew my arm was healthy and it was just a matter of trusting that it was healthy and going out there and making my pitches."
The start against the Brewers assured manager Jim Tracy that Cook, a 2008 All-Star, was completely back and ready to help anchor a starting rotation that needed some help, especially after Jason Marquis faltered in September and Jorge De La Rosa suffered a groin injury in his last start against the Dodgers.
De La Rosa isn't on the roster for the NLDS against the Phillies, making the return of Cook -- and a healthy Cook, at that -- even more paramount to the Rockies success.
"When I saw the start last Thursday against the Milwaukee Brewers, it was the Aaron Cook that we have --- as the Rockies have grown accustomed to seeing when he's on his game in that manner," Tracy said. "Tremendous sinker, great competitor."
Ah, the sinker, Cook's pitch of choice, the one that served him well in 2008 when he won a career-high 16 games and made his first All-Star appearance and one that was, to be sure, serving him well again until he left a start on Aug. 21 with a sore right shoulder.
When Cook is on, he almost mesmerizes hitters with his sinker and ability to pound the strike zone. On July 1, 2008, Cook needed 78 pitches for a shutout over the San Diego Padres, getting 15 ground-ball outs along the way.
The year before, Cook did nearly the same thing to the Padres, throwing 61 pitches over the final eight innings in a 10-2 victory where he got 16 groundouts. This shows what Cook is capable of when he's dealing and getting hitters to chase the sinker.
But all that was taken from him when he landed on the disabled list in August. Luckily for Cook, his rehabilitation was devoid of any snags or setbacks.
"I trusted the trainers a lot, went out there, did my rehab, and got back to the point where we were able to mix in the first start and throw 75 pitches, and second start, I think I got up to 85 or 88," Cook said. "It was nice to get out there."
Cook figures to need his full arsenal of pitches, sinker and all, against a Phillies lineup filled with potent left-handed bats. Then there's the matter of how Philadelphia led the National League in home runs (224), including a including a league-best 108 home runs at its home ballpark.
"For me, I'm a ground-ball pitcher, so if I'm getting fly balls, I'm not really doing my job. I've been fortunate to come up to Colorado where you have to learn to pitch, to contact, and keep the ball on the ground as much as possible," Cook said.
"When I come into a place like this [Citizens Bank Park], I really don't worry as much about the ballpark or the power alleys or how short the fence is, I really worry about getting my sinker down in the zone and getting the ball in play, because I rely on my defense behind me and they've made great play after great play all year."
Corey Brock is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.