Reflections of the Big Unit - MLB - Yahoo! Sports

Greg Maddux, one of two active pitchers (Tom Glavine is the other) with more career wins than Johnson, said he’d seen more splitters out of Johnson and that the pitch looks more and more like a changeup. Adam Dunn, who now has seen both sides of Johnson, said Johnson has become less predictable.

“From what I’ve seen, he’s commanding all of his pitches,” Dunn said. “Back in the day, when he got down 2-and-0, you knew a heater was coming. Not anymore. I can only imagine how tough that is on hitters. I think he’s pitching.”
This is what really stand out in the article. He's no longer trying to blow people away but becoming smarter in the way he goes about his business. His stuff is still effective and could probably go 1-2 years more before calling it quits.