Doosan Bears' sidearm pitcher Choi Won-joon likes to live high in the strike zone. He threw his fastball about 58 percent of the time last year, and about 40 percent of those pitches sat in the top of the zone.

Until last year, Choi wasn't always getting strike calls on those pitches. But things are expected to change this upcoming season, with the Korea Baseball Organization (KBO) set out to expand the zone. Umpires have been asked to start calling strikes on those high pitches, and that's music to Choi's ears.

"I've read stories about how umpires ended their winter break early to start training their eyes on the new zone," Choi said in a phone interview Thursday. "One umpire was quoted as saying the zone expanded by the width of a ball in the upper part. That's great news for me."

Choi had a ground ball-to-fly ball ratio of 0.51 last year, the lowest among all qualified starters. Choi is an extreme fly ball pitcher because he throws so many pitches up in the zone.

"I started throwing high fastballs more last year and I had some success with them," said Choi, who went 12-4 with a 3.30 ERA in his first season as a full-time starter.

His own catchers with the Bears saw benefits of those high pitches. Then when Choi went to the Tokyo Olympics, veteran catchers on the national team also recognized value in those high fastballs.

"I had many of those pitchers get called for a ball, but if I can get those calls in my favor this year, it will make my life so much easier," Choi added.

And to complement those high fastballs, Choi said he will start working on his curveball. As a reliever, Choi used to throw the curve more often. But in 2021, he only offered it 2.4 percent of the time as the least-used pitch in his arsenal.

"I don't have that much conviction in my curveball just yet, but I've been working on it consistently this winter," Choi said. "I will also polish up my changeup. If I can drop those two pitches low in the zone, then my high fastball will be that much more effective."

Choi tossed a career-high 158 1/3 innings last year and said his goal for 2022 is to surpass that total.

"I think I should throw at least 180 innings to be considered an ace. I am not at that level yet," Choi said. "First, I will try to get to 160 innings. Then I think high win total and low ERA will follow." (Yonhap)