Of course, this now means the Chargers offensive line will go through a bit of a shuffle in the lieu of Slater's absence.
Harbaugh said Friday that the Chargers best five, from left to right, are Alt, Zion Johnston, Bradley Bozeman, Mekhi Becton and Pipkins.
It's the group they'll roll with as it stands from this point forward.
"That's where we'll start," Harbaugh said. "Nothing is set in stone, but that's where we're at."
With Alt shifting to the left tackle spot, he reverts back to the position he knows well.
The No. 5 overall pick in last year's draft spent his collegiate career manning down the quarterback's blind side before moving to the right side in his rookie season.
He impressed on the right side, posting a 94.3 percent pass-block win rate, according to ESPN, which was the fourth-highest mark among offensive tackles in the regular season.
Harbaugh had nothing but high praise for what Alt can do now switching sides in his second season.
"He's one of our top guys, elite player on the team," Harbaugh said. "Great player. He's been ascending as much as anybody on the team. People ask me, 'Who's the most improved guy?' It could be Joe Alt, and he was really good last year.
"He's really trained and doing a heck of a job," Harbaugh said.
Alt does also have some NFL experience at left tackle as he suited up at that position in Week 18 last year against the Raiders.
The result? A game where he allowed zero pressures and had the sixth-best Pro Football Focus pass blocking grade (83.7) of the week among all tackles.
"I've played both sides now, I've played right and played left, so I'm comfortable on both," Alt said. "It just breaks down to reps, repeated reps.
"Making sure muscle memory is there and really the quickness I got to do out of my stance is what I have to work on," Alt added.
The team has full confidence that Alt will continue to approach this task just like he has every step of the way in his young NFL career.
"Joe is a competitor, he's just like Rashawn," Pipkins said. "He'll attack any opportunity you give him. He's going to be great, he's as confident as he can be.
"He played it in college and he's just going to go back out there and get after it," Pipkins added.