Valentine lauded reliever Andrew Miller, who has had a break-out year in the Boston bullpen.
Miller is 3-1 with a 3.29 ERA while limiting opposing hitters to a .191 batting average. He's also stranded 37-of-42 inherited runners, good for an 88.1 success rate, third-best among American League relievers.
"I think Andrew's developed into a terrific pitcher," said Valentine. "I think he started in a very questionable place and now has a very secure foot-hold on being able to compete at the major league level. I think he can be a dominating force in the bullpen."
Lefties are hitting just .134 (11-for-82) off Miller this season and he's registered 47 strikeouts in 38 13 innings and has held opponents scoreless in 40 of his 49 appearances.
"He can be very proud of his development," said Valentine. "And he's still developing. He's working on a two-seam changeup to righthanders that I will think will put him a little over the edge next year, into another
Miller has had some difficulty with righties, who have hit him at a .278 clip. Hence, the work on the changeup to give him another weapon when facing righties.