Kansas City, Mo. ? The Kansas City Royals sent left-hander J.P. Howell, their best minor-league pitching prospect, to Tampa Bay on Tuesday for outfielder Joey Gathright and infielder Fernando Cortez.

Royals’ manager Buddy Bell said Gathright would play center field and current center fielder David DeJesus would shift to left field when both are in the lineup, which could happen as soon as Wednesday.

It’s the first deal engineered by Dayton Moore since he took over as Royals general manager June 8.

Selected as a sandwich pick between the first and second rounds of the 2004 draft, Howell was 3-5 with a 6.19 earned-run average in 15 games for Kansas City last season.

“J.P. Howell is a guy our people liked,” Moore said. “But at the same time the best way for us to improve our pitching is to improve our defense, and Joey Gathright speaks to that element of what we’re trying to do here with speed and defense and pitching. You’ve got to give up something to get something.”

Howell, 3-2 with a 4.75 ERA in eight starts this year with Triple-A Omaha, will report to Triple-A Durham for the Devil Rays.

“He’s someone we project to pitch in the rotation for us at some point,” said Andrew Friedman, Devil Rays executive vice president of baseball operations.

Gathright is the key to the deal for the Royals. He started the season with the Devil Rays, hitting .201 with 12 stolen bases in 55 games before being optioned to Durham on June 6. Cortez had a .222 batting average in 60 games with Durham this season and will probably be groomed as a utility infielder for the Royals, who began play this week with a major league-worst 19-49 record.

“We’ve got to make sure that we’ve got outstanding defense in this ballpark. With DeJesus and Gathright we certainly have some guys who can track the ball,” Moore said. “We’ve got to be athletic in this ballpark.”

The Royals feel Gathright has potential to improve his offense.

“He’s always hit throughout the minor leagues,” Moore said. “He’s had a high on-base (percentage). This year he was struggling a little bit. He’s one of those guys who’s a developing offensive player. The one phase of his game that will show up every day and contribute to our lineup is the speed element. I think his offense will play up in this ballpark because of the vastness of the alleys.”

The Devil Rays also optioned Seth McClung to Durham, a move designed to see if the right-hander can go from the rotation to a future role as a closer.

McClung went 2-10 with a 6.81 ERA in 15 starts this year. His fastball can reach the upper 90s.

“You look at my stuff, it’s good,” McClung said. “I know it’s good. I just have to learn how to harness it.”

There is no timetable for when McClung will rejoin the Devil Rays.

“We just felt it was the right time to make this particular move,” Tampa Bay manager Joe Maddon said. “He was not difficult to persuade. We just thought it was the right thing to do.”