The Mets are retaining an arm and his brain. 

Robert Stock, a veteran who served as rotation and bullpen depth last season and is among the most data-literate baseball players around, will return on a one-year major league contract, the Mets announced Friday. 

Last season, Stock required surgery for thoracic outlet syndrome in March, pitched in eight minor league games while building up in June and July and then earned a major league look as the Mets sold at the August deadline. 

Stock’s stint was a roller coaster but apparently showed the Mets enough: He pitched in relief once and started seven times, with four excellent outings in which he allowed one or zero runs.

In the other three, he was hammered for 18 earned runs in 11 innings, which were to blame for his season-ending 5.93 ERA. 

His season ended early, hitting the injured list in mid-September with finger numbness that he did not believe was serious. 

“I have proven that my name should be in consideration for being a major league pitcher,” Stock said at the time. “There are a million things I want to do better.” 

A true journeyman who originally was drafted in 2009 and is turning 37 later this month, Stock has pitched for the Long Island Ducks, in the KBO, Mexico and plenty of spots in between and has been public about using the growing technology in the game to get better.