For 1 2/3 innings, the pitch was nearly unhittable. But when Cook moved to cover home plate after a passed ball, he suffered a nasty gash on his leg as Chris Davis stomped on him with his cleats.
From that point, Cook was never the same. It was another mutation of the strokes of bad luck — in terms of injuries — that have plagued the 33-year-old pitcher over the recent stretch of his career.
"My knee in front of my leg was kind of numb, so I was really just out there throwing all arm," Cook said. "That's when you start to see the ball get flat. It's just up in the zone. Just made bad pitches after that. I probably could've thrown a little bit slower and got it down in the zone, but it was just one of those days."
Cook entered Saturday's 8-2 loss as healthy as he's been in years. He showed those strides in the first inning, tossing nine pitches and getting three consecutive groundouts to shortstop Mike Aviles.
After the collision with Davis, Cook limped into the dugout with the medical staff before eventually returning to the mound. Eleven stitches later, Cook was rendered ineffective.
"I think after the injury, the sinker was up," catcher Jarrod Saltalmacchia said. "He was leaving it up a little bit. For a sinkerball pitcher, that's never good."
It was the same old story again for Cook, who has battled shoulder problems, a broken finger, a broken leg and a pulmonary embolism. To his credit, he attempted to tough it out despite the drops of blood on his uniform.
Cook told Red Sox manager Bobby Valentine he was ready — shortly after a brief examination in the dugout — and to not call in Clayton Mortensen, but Cook was a shell of his first-inning self.
"I think it affected him a lot," Saltalamacchia said. "You got to change your emotions a little bit, just a lot of stuff goes on when you have a hole in your knee. I could basically see the whole inside of his leg, so it was pretty nasty … ligaments, tendons."
With the string of injuries sidetracking him, Cook is fighting to stay positive. That mentality has carried him through the past few years.
"It's just the way life is," Cook said. "We were out there, I was trying to make a good baseball play. I was trying to stop in front of the plate. That's why I slid. It's just one of those things that happens. It's part of baseball."
His role on the Red Sox' roster is unknown moving forward. Despite his promotion, the questions continue.