MILWAUKEE -- Zach Eflin appeared to be just hours away from returning to the starting rotation last month after dealing with a knee issue. Now, it’s uncertain if he will be able to pitch for the Phillies by the start of next season.

Eflin will have surgery Friday to repair a tear in his right patellar tendon for the second time in five years, and the Phillies said he will require six to eight months of recovery time. The 27-year-old right-hander had both patellar tendons repaired in 2016.

“Sure, there’s a concern,” president of baseball operations Dave Dombrowski said when asked if the team was worried that Eflin was having the surgery a second time. “It’s a major surgery. He’s out six to eight months. Nobody has said that his career is threatened, but sure it’s a concern. There’s a key guy for us that you’re talking about being six to eight months. It’s a long time and it’s a major surgery.”

Six months would have Eflin back on the mound during spring training. Eight months would keep him out until May. In 2016, Eflin had his right knee repaired on Aug. 19 and his left knee on Sept. 30. He made two minor league rehab starts in April 2017 -- less than seven months after his second surgery -- and rejoined the Phillies three weeks into the season.

Eflin made his last start July 16. The Phillies recently have filled rotation spot by using a cast of relievers every fifth day instead of a traditional starting pitcher. It worked for a win on Sunday and they’ll try it again Friday against Colorado.

Eflin’s recovery timeline could force the Phillies to change course this winter when it comes to starting pitching. It was practical to think they could begin next season with Eflin, Zack Wheeler, Aaron Nola, Ranger Suárez, and Kyle Gibson. But that now seems like lofty expectations. This could lead them to acquire a starting pitcher.

“Well, I’m sure it will change our discussions for sure, but I’m not at that point yet,” Dombrowski said. “But sure, because we felt we were ready for five to start for opening day. And I guess technically you could be, because I said six-to-eight months, but I’m sure we’ll have a lot of future discussions on this. It’s just not the time right now for that.”

The Phillies had hoped Eflin’s injury would recover this year with rest and a series of platelet-rich plasma injections after he was placed on the injured list July 20. A month later, he made a minor league rehab start and was set to join the major league rotation on Aug. 26.

The night before, Eflin said he was ready and the Phillies cleared a roster spot the next morning by designating Chase Anderson for assignment and eventually releasing him. Anderson had struggled, but the Phillies would not have dumped him had Eflin not believed he was OK to pitch.

“We got pretty far down the road. We got really close,” manager Joe Girardi said. “But I think it just wasn’t meant to be.”

Extra bases

The Phillies named infielder Bryson Stott their minor league hitter of the month after he hit .408 with a 1.108 OPS in 114 plate appearances with double-A Reading. Reading right-hander James McArthur was the minor league pitcher of the month, and outfielder Matt Vierling, who is now with the Phillies, was the defender of the month. ... Hans Crouse, the pitching prospect acquired from Texas in the Spencer Howard trade, was promoted to triple A after five starts with Reading. The right-hander had a 3.42 ERA in five starts. He turns 23 next week. ... Suárez will start Thursday against Rockies right-hander Antonio Senzatela.