Why the 49ers’ Starting Left Guard Spot Is Still a Fluid Situation

Nothing is cemented yet.

Sep 11, 2026; Melbourne, AUS; San Francisco 49ers head coach Kyle Shanahan in the first half at Melbourne Cricket Ground. Mandatory Credit: Kirby Lee-Imagn Images | IMAGN IMAGES via Reuters Connect

The starting left guard spot for the San Francisco 49ers was one of the most intriguing aspects to pay attention to in Week 1.

Not a single player was able to separate themselves and win the job. It’s why the 49ers didn’t decide who would be the starter until the week of the game against the Los Angeles Rams.

Surprisingly, the 49ers went with their first option when they began training camp — Connor Colby. It seems he was the default player all along, which is what the unofficial depth chart revealed.

Colby didn’t take a single snap in the preseason at left guard, so the fact that he was starting was head-scratching. Offensive coordinator Klay Kubiak hinted at a rotation for weeks. 

I was sure that’s what the 49ers would implement. They did it a few seasons ago when no one could win the starting right guard spot. However, giving Colby the start panned out. He performed well against the Rams.

Considering they’re supposed to be a vicious defensive front, Colby was sound. He didn’t get flagged at any point and wasn’t visibly a liability like he was last season in his starts.

A performance like that would typically cement a player as the starter, and while he’s certainly helped raise his stock, the starting left guard spot is still a fluid situation. All it takes is for Colby to mess up in one of the next few games. 

Maybe the 49ers give him some leeway, but I don’t imagine it's a lot, especially if he’s single-handedly hurting the offense. The 49ers will easily swap him out for rookie Carver Willis or Robert Jones.

Rotating players at left guard will also come into play. Colby is by no means the settled starter. He’ll need to stack several games in a row of solid performances to do that.

If it’s up and down, a rotation will come into play. If it’s mostly down, either Willis or Jones will take over, or they will both be in a rotation for the starting spot. It can go a few ways. 

For now, I think Colby is safe for the next couple of games. Part of it is that I think the 49ers will give him the runway to establish himself, and their opponents are the lowly Miami Dolphins and Arizona Cardinals.

It’s not until the 49ers play the Denver Broncos that Colby will potentially be put on notice. If he does well in that game, he’ll likely hold onto the starting spot for the majority of the season.