Matsuzaka also pointed to a deeper knowledge of big-league hitters and the different ways to attack each individual slugger with his trademark array of pitches.

"Last year it was like I was trying to feel my way through the dark when I was facing the batters for the first time," Matsuzaka said through translator Masa Hoshino. "This year I'm a little more familiar with what I'm up against, and it's affecting my pitch selection toward certain hitters. And that's some of what you're seeing this year."

Despite a frustrating outing Wednesday afternoon in which Matsuzaka was out of the game after six innings with a high pitch count, he remains unbeaten in his last seven starts -- a stretch during which he's gone 5-0 with a 2.54 ERA.

The early exits seem to be the only legitimate criticism of Matsuzaka, and they have been a baseball fact of life the Red Sox have learned to accept. Some days will be like Wednesday -- full of walks, strikeouts and high pitch counts -- and other times he'll show why he's posted a 2.21 ERA against potential AL playoff squads.

"As he gets deeper into the season, his stuff continues to improve. We're seeing a guy that feels good about himself both mentally and physically," pitching coach John Farrell said. "It's easy to say that we'd love for him to get into the seventh or eighth inning every time out, but the fact remains that he's leaving games with a lead nearly every time out.

"If it is six or seven innings every time out, then he's probably only giving up one or two runs during that time. "He's been dominant for the vast majority of the innings that he's thrown for us this year."