“Knocking the cover off the ball,” Phillies manager Pete Mackanin said on Wednesday afternoon at Citizens Bank Park. “He’s doing very well.”

But it might be a while before Alfaro is promoted, even if he keeps hitting well. Alfaro, 23, is in his final option year, meaning beginning next season, the Phillies cannot send him to the Minor Leagues without risking losing him.

#Phillies No. 3 prospect Jorge Alfaro continues torrid start with four RBIs, three hits for @IronPigs. https://t.co/BYcZkv3E9K pic.twitter.com/WCsLIePMI0

— MiLB.com (@MiLB) April 26, 2017

Because of that, the Phillies might prefer to have Alfaro play regularly at Triple-A, in preparation for what could be a prominent role in 2018. Obviously, that does not apply come September, when rosters expand or if there is an injury to Cameron Rupp (.657 OPS in 52 plate appearances) or Andrew Knapp (.594 OPS in 20 plate appearances).

Alfaro still needs work offensively. The Phillies wanted to see him make more contact this season, and so far he has, but he has walked once compared to 17 strikeouts. Defensively, he still has room to grow, although Mackanin said reports indicate improvement.

“He had some issues defensively,” Mackanin said. “He wasn’t getting down enough, and he worked on that all spring. He’s a big guy, and it’s a little more difficult for a big guy to get low and just be a little more quiet behind the plate; less movement.

“And he certainly doesn’t need a lot of work on his throwing, because he’s got that howitzer for an arm. He’s doing well blocking balls. He’s doing everything well right now and hitting on top of it, so that’s a nice sign.”