Two months after retiring as an NFL player, Matthew Slater rejoined the Patriots as an advisor to new head coach Jerod Mayo last April.

So what has Slater been up to since? Mayo answered that question before Tuesday’s OTA practice.

“Everything. Like, seriously, he’s a catch-all,” Mayo said. “Remember, we came in together (in the Patriots’ 2008 draft class). We’re like brothers. He played a lot longer than me, and I’ve said this before: who knew Slate should be a gold jacket guy? Who knew at that time? We think very much alike.

“What I will say is at this level, it’s hard to find people that tell you the truth, and he’s one of those guys that, he’ll let me know what it really is.”

Slater has been described in other reports as Mayo’s “right-hand man.” The former special teams captain spent his entire playing career in New England after entering the league as a fifth-round pick out of UCLA, a day after the Patriots selected Mayo in the first round of the 2008 draft. Slater, 38, contemplated retirement for several years before hanging up his cleats this offseason.

Extra points

New Patriots wide receiver David Wallis, an undrafted rookie from Division III Randolph-Macon, participated in his first practice Tuesday. The Pats signed Wallis on Monday after he attended the team’s rookie minicamp last month on a tryout basis. To create a roster spot, the front office released backup offensive tackle Andrew Stueber, a 2022 seventh-round pick who spent last season on the practice squad. … Asked about his initial impression of the Patriots’ defense, free-agent addition and defensive tackle Armon Watts said it has “a high ceiling.” … Asked what he’s learned about his new offensive staff and system this spring, Mayo told reporters Tuesday: “I would say just the overall intelligence. Look, we have a very competent staff, I would say, on all sides of the ball.”