By Larry Fine

NEW YORK (Reuters) - Justin Verlander has always had an electrifying arm but it took time for the 28-year-old right-hander to graduate to the ranks of mature mound ace, Detroit Tigers manager Jim Leyland said on Thursday.

Leyland will send Verlander to the hill to duel New York Yankees left-hander CC Sabathia in the opener of their best-of-five divisional series in the Bronx on Friday.

"One of my favorite lines is you can't make a senior out of a freshman. It takes time," Leyland told reporters at Yankee Stadium on the eve of the playoff series. "You have to nurture players.

"You have to go through different experiences, I think, before you really get to the peak of competition, or your ability, or your own mind-set, or your own peace of mind.

"I think all players have to go through that. I think you have to suffer through some adversity before you ever figure it all out."

Verlander would be worthy of a pitching PhD after a 24-5 season in which he led the league in wins, earned run average (2.40), strikeouts (250) and 251 innings pitched that included a no-hitter in May against Toronto.

The right-hander burst on the scene in 2006, going 17-9 with a 3.63 ERA to help pitch Detroit to the World Series. Since then, he suffered an 11-17 season in 2008 before finding his dominant form.

"I think Justin has pretty much taken it step by step," said Leyland. "He had the big year in 2006. Then he went through a little bit of a humbling period.

"He's made adjustments mentally, he's made some adjustments physically. He's figured some things out, that you don't have to throw it 100 miles per hour every pitch.

"You can pitch to contact a little bit more at times and save it for when you do need a strikeout. He's matured a lot."

Verlander agreed.

"I'm a totally different pitcher now, as opposed to back then," he told reporters. "Just being a rookie and wide-eyed and first experience in Major League Baseball, first experience in the postseason. It was quite an experience for me.

"Looking back at that now, I can kind of take it and use it to my advantage as to what to expect."

Verlander, who was four outs away from another no-hitter against the Los Angeles Angels in July, has not yet taken stock of his standout season.

"Once the last pitch is thrown, hopefully after we have won a World Series, I can sit down and look back at it and enjoy it. For right now, I'm focused on Game One."

(Editing by Ian Ransom)