OAKLAND, Calif. (AP) With a shortened swing and newfound swagger following his most rigorous offseason of training yet that helped him pack on 15 pounds of muscle, Yoenis Cespedes wants to forget all the frustrations of last year.

While the slugging left fielder has turned his attention to making better, more consistent contact, he still plans to regularly clear the fences for the Oakland Athletics - and the reigning Home Run Derby champion hopes that means hitting more than the 26 long balls he had last season.

''Possibly, I'll have a little less power. If a home run went 430 feet, it will go 410 feet,'' Cespedes said with a chuckle. ''But maybe I can do it more often.''

As Cespedes looks back now on what he considered a subpar second season in the majors, he points to not being ''strong in mind'' dealing with the ups and downs.

He became an unlikely Home Run Derby winner at the All-Star game while celebrating his family's long-awaited arrival to the Bay Area, but dealt with injuries and a notable decline in batting average.

''I think I should have been stronger mentally,'' Cespedes said leading into Saturday's FanFest. ''As an athlete, when things aren't going your way, you have to be strong-minded. Maybe that was one of the reasons I didn't so well last year.''

So motivated was Cespedes, he took his offseason training up a notch.

Not in volume, but rather the intensity in which he worked out this winter in South Florida.

While the 28-year-old Cuban defector has two seasons remaining on the $36 million, four-year contract he signed in February 2012, Cespedes indicated Friday he is eager to lock up a long-term deal and even consider spending his career with a club he helped win improbable back-to-back AL West crowns.

''You're always going to have highs and lows. Last year I got into this low and just couldn't recover the whole season. In 2012, I had highs and lows,'' Cespedes said.

Now, he plans to better deal with those moments. The A's are pleased with that growth.

''Obviously, there's some toughness there, you see a guy that shows up in the big games and gets inspired by the big stage,'' manager Bob Melvin said Saturday. ''Sometimes it's tougher on guys with that kind of talent to go through some struggles and there maybe needs to be, in his mind, some more fight to get through that. I think that's maturity.''

Cespedes reflects on how he made more contact over the final month last fall, but decided to spend much of the offseason working on a more compact swing.

''I didn't do anything different, it was the same. I trained a lot harder than last year,'' Cespedes said. ''I did more exercises on the field and in the gym to gain strength. Last season was a little worse than the first one and I know I can do a lot better. That's why I'm preparing a lot hard and stronger for this year.''

While Cespedes' batting average dropped to .240 last season after he hit .292 with 23 homers and 82 RBIs as a rookie, he still finished with 26 homers and drove in 80 runs in 2013.

But he acknowledges pitchers caught on to him a little bit last year, then he began to make strides again down the stretch in September when he focused on making contact.

''My first year, they didn't know me as well and pitched me one way and the second year they knew me a lot better and I was not capable of making the adjustments I needed to do,'' he said. ''I'm looking forward to making those adjustments.''

He has already made one: Cespedes says he is weighing in at 225 pounds, some 15 higher than his listed playing weight last year.

''The thing that resonates with me is talking about shortening his stroke some, and he has done that at times and has had success with it,'' Melvin said.

Cespedes speaks of making small changes, including listening to some of the people around him and heeding their advice - from countryman and comrade Ariel Prieto to hitting coach Chili Davis, reliever Ryan Cook and center fielder Coco Crisp.

''They tell me little things but it means a lot to me,'' Cespedes said. ''The main goal this season is to concentrate on going to home plate and making good contact with the baseball. This winter I worked precisely on having a shorter swing to make sure I make more contact. I think this is going to work well.''

Davis saw the adjustments Cespedes made late last season and in the playoffs, when he batted .381 with a home run and four RBIs in a five-game division series defeat to Detroit.

''What'd I'd like to see is that determination, the approach, the focus, day in and day out,'' Davis said. ''If he can maintain that throughout the year, there's a chance you'll see some incredible numbers from him, because he's that good.''

Cespedes has taken consecutive AL division series losses to the Tigers personally. He expects himself to do more, and he is already calling for the A's to get back to the playoffs in a division featuring big-name new faces such as Robinson Cano in Seattle and Prince Fielder transplanted to Texas.

''I don't know if we're the favorite,'' he said, ''but the A's are going to be in the playoffs again.''