"He has looked . . . " Yost said.
2010 Spring Training - null
Sights & Sounds
Spring Training Info
That could translate into fantastic news for Royals fans, who last year saw a beefy O'Sullivan arrive in a trade and join the rotation with unremarkable results -- a 3-6 record and a 6.11 ERA in 14 games.
"I needed something to change," he said.
So he did something about it, changing his size for one thing. He lost more than 20 pounds.
"I'm trying to become a smaller guy," he said. "I'm trying to make things easier for myself."
He donned his grandpa's old apron and politely took charge of the kitchen from his wife Sabrina in their California home.
"I started cooking for myself. That's where I made my best decisions," O'Sullivan said. "I like to cook, I really enjoy cooking. But to go out to eat, you're leaving the menu options up to somebody else. So if I go to the store and buy stuff and I can make it, I know what's going into the food."
Off came the weight and on went sessions with his personal trainer.
When O'Sullivan came to Spring Training, he brought with him memories of a down-and-up season after he arrived from the Los Angeles Angels with pitcher Will Smith in a deal for third baseman Alberto Callaspo.
"There was a three- or four-game stretch there in the middle, maybe five games, when I was awful. I was really unhappy with the way things were working out. The things we were working on, I was using them in the game but they weren't clicking yet. Things weren't exactly going the way they should," he said.
Then, in his last three starts, he went six innings in each game, gave up a total of just three runs and went 2-0 with a no-decision.
"At that point, I was wishing that I had more season because it's finally working," he said.
Pitching coach Bob McClure worked with O'Sullivan to eliminate a couple of pauses in his delivery. ("It's hard to do anything from a dead stop," McClure said.) Now he's much smoother with the ability to keep his pitches low in the strike zone.
"This kid has come in and it's a different pitcher than what left last year," Yost said. "In all of his sessions, in everything he has done, he has looked great. He's keeping the ball down consistently, he's changing speeds, he's shortened his stride, he's adjusted his delivery. There's not the inconsistency with the balls up that we've seen."
Yost was no less impressed after O'Sullivan's first Cactus League appearance, in which he whizzed through two innings against the Los Angeles Dodgers. He gave up a single but got a double play and faced the minimum six batters. O'Sullivan will get his second outing on Monday night, a start against the San Diego Padres in Peoria, Ariz.
"Less margin for error with the new delivery we've been working with," O'Sullivan said. "The ball's been consistently down. The offspeed stuff has been crisp. It takes a whole lot of pressure off my arm as well, with the whole body working together instead of, at some points in my delivery, working against itself. So it ought to give more longevity into the season."
O'Sullivan is trying to stay in the rotation but there are six leading candidates for the five spots, and that's not even counting some of the kiddie corp prodigies that might wedge their way in.
What's often forgotten is that O'Sullivan is still a kid, too, just 23. But he's got the edge of 31 big-league games in the last two years with the Angels and Royals.
And this year there's less of him to move around.
"I feel lighter on my feet, it's easier to do things," he said.
If it's easier to win games, the Royals will be all for it.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.