A's acquire Mets' No. 15 prospect Meisner

The A's acquired All-Star right-hander Casey Meisner, the Mets' No. 15 prospect, in a trade that sent veteran reliever Tyler Clippard to New York on Monday afternoon.

Meisner, 20, is 10-4 with a 2.35 ERA in 18 starts between Class A Advanced St. Lucie and Class A Savannah this year. The Mets' 2013 third-round pick out of Cypress Woods High School in Texas has struck out 89 batters and walked 33 in 111 innings this year, mostly with the Sand Gnats. He was a South Atlantic League All-Star earlier this season.

The righty, who reportedly increased his fastball velocity this past year from 90 to 94 mph, was promoted to St. Lucie on June 27 and has allowed three earned runs or fewer in all six of his Florida State League starts this summer.

The 6-foot-7 starter debuted with the Mets' Rookie-level Gulf Coast Leauge affiliate in 2013 before spending last year with Class A Short Season Brooklyn, where he finished 5-3 with a 3.75 ERA and 67 strikeouts in 62 1/3 innings.

According to MLBPipeline.com, Meisner "complements the improving fastball with a big curve, and he has shown an excellent feel to spinning the ball. While his changeup is behind, he's shown some feel for the off-speed pitch as well."

The 20-year-old held Tampa to three hits and a run in his FSL debut on June 27, pitched six scoreless innings against Lakeland on July 13 and struck out eight over five innings in Charlotte on July 20. He went five innings and took the loss to Daytona on his final outing as a Met on July 26.

His best outing of the year came on May 21, when he struck out a season-high 10 and held Rome to one hit over seven scoreless innings for Savannah. The righty turned in a pair of double-digit strikeout efforts last summer, whiffing a career-best 11 batters on Aug. 26, 2014 against Staten Island. He fanned 10 vs. Vermont last Aug. 17.

"I'm just trying to improve every outing I throw, no matter if it's good or bad," Meisner told MiLB.com on July 13. "You're always going to make a bad pitch or…do something wrong on the mound, in a great game or a bad game. You just have to pick out the good things that you did and you have to capitalize on those."

Clippard, 30, heads to the Mets along with $1 million, meaning New York will be on the hook for $2 million of Clippard's salary this year. The veteran reliever is 1-3 with a 2.79 ERA and 17 saves in 37 appearances this year with Oakland. The former Nationals closer has struck out 38 and walked 21 in 38 2/3 innings.