Miami Dolphins backup quarterback Quinn Ewers suffered a new injury early in his action in Friday’s preseason opener against the Washington Commanders, according to a league source. While not disclosing the specific ailment, the source said Ewers will be week to week. As Ewers was working as the Dolphins’ No. 2 quarterback in training camp, the Dolphins brought back fellow quarterback Mark Gronowski, signing him Sunday. Gronowski, the undrafted rookie out of Iowa, was Miami’s fourth-string quarterback behind Malik Willis, Ewers and Cam Miller earlier in camp, but his struggles had him waived last week. Now, he returns as the No. 3 passer. Ewers had already been dealing with a separate undisclosed injury earlier in camp but one he was working through, according to the source. Ewers struggled significantly Friday in Landover, Maryland, completing just 1 of 8 passes for 27 yards and an interception. Dolphins coach Jeff Hafley said Saturday that Ewers’ performance was not up to standard, but not all of it was on the second-year quarterback. “The interception that he threw clearly wasn’t a great decision, especially in that point of the field,” Hafley told reporters in a web conference Saturday. “I pointed it out in the team meeting. When you’re back there on third-and-7, you got to protect the football and if we punt it, it’s okay. We can’t make those mistakes. “At the same time, I showed the team in the team meeting (Saturday), there were two examples where Quinn was playing quarterback where, play pass on his first hitch, he threw a great ball that would have been about a 25-, 30-yard explosive, maybe more. And the receiver broke out and he should have hooked up, and that’s an example of now the ball is moving forward, now Quinn’s got some confidence and here we go.” Third-string quarterback Cam Miller also struggled, going 3 of 11 for 39 yards, but he also had multiple targets drop catchable passes. Elsewhere, offensive lineman Jamaree Slayer was placed on injured reserve Sunday, effectively ending his season. Salyer had been out since early in training camp with an undisclosed injury. He joined the Dolphins this offseason to either compete for a starting role or at least be a top reserve offensive lineman. The line depth may have found some outside help in the addition in the past week of Caedan Wallace, in a trade with the New England Patriots. The Dolphins also waived second-year cornerback Ethan Robinson with an injury settlement. They signed linebacker Cam Riley.