DETROIT -- Much was made of Jeremy Bonderman's attempt to develop a changeup during Spring Training this year.

It was thought that a third pitch to add to his fastball and slider would elevate Bonderman's game and develop him into one of the game's elite pitchers.

For whatever reason, that pitch hasn't developed to the point where Bonderman uses it frequently, and his results have suffered, culminating in Saturday night's 5 2/3-inning, seven-run, zero-strikeout performance against the Yankees.

"Once in a while, you get a sign -- in Spring Training, I was excited because I thought it was coming around," Tigers manager Jim Leyland said. "For whatever reason, it hasn't come around with any consistency. You haven't seen guys fooled with a swing and miss."

Bonderman had improved his ERA in each of his first four seasons with the Tigers. It was 5.56 in his 33 games as a rookie in 2003 and fell to 4.08 in 34 starts last season. His ERA has risen to 4.87 this year.

While Leyland admitted he isn't the ultimate authority on Bonderman's recent struggles, he said that the lack of a third pitch would be his reason for the issues if he were an impartial observer.

"He has two very good pitches, but you have to be able to throw a swing-and-miss changeup," Leyland said.

The struggles may also be a result of too much pressure on Bonderman, though Leyland said that any perceived pressure results from Bonderman himself.

"I just want Bondo to be Bondo," Leyland said.

Still no Sheff: Gary Sheffield was not in the lineup for the fifth straight game as he continues to deal with an ailing right shoulder.

"This is my time of the year," Sheffield said. "This is when it's fun for me. This is the time when I love playing -- I love going out there when it really counts."

Sheffield said he realizes that doctors will likely need to shave down some of the bone in the shoulder -- a procedure he has already undergone twice -- but he wants to wait until after the season before considering that option.

"I know my shoulder so well," Sheffield said. "I know when it's something I can continue exercising or getting treatment then say, 'OK, I can get to a point where I can play.'"

Sheffield said he isn't sure if he will travel with the team to Kansas City for its three-game series with the Royals.

Still working: Kenny Rogers threw in the bullpen before Sunday's game as he continues to rehab from a sore left elbow. He has been on the disabled list since July 26.

The bullpen session didn't yield enough confidence from the Tigers' coaching staff to put a timetable on Rogers' return.

"I haven't shown them enough to where they're impressed," Rogers said.

Rogers will throw another session on either Tuesday or Wednesday. He said there weren't any setbacks on Sunday, but that he continues to struggle with his control.

"It's slowly improving," Leyland said of the recovery process. "That's the word I get."

Just a number: Don't go out and buy a No. 4 Cameron Maybin jersey just yet. He said he likes the number, though it isn't his first choice.

"That's what they gave me when I got here," Maybin said. "I was going to wear whatever they gave me. No. 4 is cool. Maybe in the future, I'll switch to a different number, but right now, No. 4 is cool with me."

Maybin wore several different numbers in the Minors, including No. 30 last year with the Class A West Michigan Whitecaps.

"I've got a couple [numbers] in mind. Maybe 24 -- that's my favorite number," said Maybin, who wears a No. 24 necklace. "Maybe 24 down the road. That would probably be the number I would like to wear. But 4 is good. Whatever they want to give me."

Mike Hessman wore No. 24 during his stint with the Tigers this year, while Magglio Ordonez has worn No. 30 since he arrived in Detroit.

Just a glove: Watch closely the next time Bobby Seay takes the mound. He wears a glove with the No. 27 sewn on the side.

No, it's not a tribute to the departed Craig Monroe, who wore No. 27 for six seasons in Detroit before he was recently traded to the Cubs. It's just the glove that Seay was issued when he made his Major League debut with the Devil Rays in 2001.

"It's my old baby. I've had it seven years -- since 2001," Seay said. "They put it on the glove, and it doesn't really come off there."

"It's worn in real nice," Seay said. "It's just had to be restrung a couple times."

Up next: Justin Verlander (13-5, 3.94) will face Mike Mussina (8-9, 5.22) on Monday night in the Tigers' final regular-season game against the Yankees this season. First pitch is scheduled for 7:05 ET at Comerica Park. The game will be broadcast nationally on ESPN 2, while local coverage will remain on FSN.