SF 49ers: Trent Williams is a priority after Anthony Castonzo retirement

There’s going to be a market for SF 49ers offensive tackle Trent Williams especially after the Colts watched Anthony Castonzo retire.

The SF 49ers‘ prospects for retaining pending free-agent left tackle Trent Williams into 2021 and beyond just got a bit tougher.

Williams, who previously indicated the Niners were still his No. 1 priority in NFL free agency this offseason, is going to have a market this spring. But the 32-year-old eight-time Pro Bowler is going to have his share of options, too.

And one of those could easily be the Indianapolis Colts now.

On Tuesday, stalwart veteran left tackle Anthony Castonzo elected to retire after a career spanning 10 years where he was a regular starter over that entire span.

Much like the Niners back during the 2020 NFL Draft, when they lost veteran tackle Joe Staley to retirement, Indianapolis is now going to be scrambling for a plug-and-play option to replace Castonzo.

For a team ready to win now and coming off a playoff appearance, the Colts will be in a good position to lure in a player of Williams’ ilk. True, Indianapolis needs to figure out some question marks this offseason, namely at quarterback and potentially a long-term replacement for Philip Rivers.

But with nearly $57 million in cap space in 2021 (fourth most), according to Over the Cap, the Colts are going to have a much easier time luring in a player like Williams once NFL free agency kicks off at the start of the league new year.

And that puts increasing pressure on San Francisco.

SF 49ers have had preliminary re-sign discussions with Trent Williams, but…

According to ESPN’s Jeremy Fowler, Williams and the SF 49ers have already engaged in contract-extension talks:

Williams would be wise to test the market, though. And at his age, this upcoming deal might be the last big-number contract he receives before retirement. According to Spotrac’s market-value tool, Williams is worth a deal in the range of $18.2 million annually.

Considering the Niners have just $22.6 million in projected cap space and will need approximately $8 million to sign their 2021 NFL Draft class, it’s not too hard to do the math and see Williams’ likely asking price won’t be easy to absorb without some serious roster shuffling elsewhere.

Should San Francisco make those moves, though?

The simple answer is: yes. Williams is a cornerstone-type piece, even at this stage of his career, and the SF 49ers don’t have any likable starting-caliber options behind him on the depth chart.

This could mean the Niners are forced into making some drastic roster changes, perhaps even moving on from quarterback Jimmy Garoppolo to generate a much-needed $24.1 million in cap space in 2021. Granted, that opens up a Pandora’s box of possibilities at the game’s most important position.

But with a team like the Colts potentially lurking for Williams’ services this upcoming season, and with no shortage of cap space of their own, they could easily look to pry the perennial Pro Bowler away from San Francisco.

Unless the SF 49ers engineer a deal sooner than later.