Indianapolis quarterback Andrew Luck retired because the Colts waited too long to provide him with the kind of pass protection that would keep him from getting beaten into oblivion.

The Texans know they have to avoid the same mistake with Deshaun Watson.

Watson was sacked 62 times last season and knocked down another 132 times. That got the Texans’ attention, making them realize how foolish the franchise had been not to focus more on the offensive line in the draft and free agency.

The Texans took a chance on veteran left tackle Matt Kalil in free agency and drafted tackles Tytus Howard and Max Scharping in the first and second rounds.

If Bill O’Brien trades outside linebacker Jadeveon Clowney for any player other than a left tackle who can step in and solidify that position for years, he’ll be making a huge mistake.

The pass rush can suffer without Clowney. The running game can suffer without Lamar Miller. But Watson doesn’t need to suffer any more than he did last season when he was treated like a piñata by opposing pass rushers.

By the time Colts general manager Chris Ballard used first- and second-round picks on guard Quenton Nelson and tackle Braden Smith last year, Luck already had a depressing list of major injuries that required multiple operations. And now he’s done at 29 because of incapacitating pain and overwhelming frustration over his body, which is, in football parlance, broken down and irreparable.

O’Brien can’t make the same mistake the Colts made. Don’t wait until it’s too late to repair the physical damage and emotional devastation that caused Luck to shock the NFL by retiring.

The Texans have Howard at left guard and Scharping at right guard. Howard’s out with a broken finger but is expected to be ready for the New Orleans opener Sept. 9. Scharping, who also played right tackle Saturday night, had his first poor performance in the 34-0 loss to Dallas.

No matter what we think about the Texans not trading up in the first round to get offensive tackle Andre Dillard (as Philadelphia did) or what we believe about Howard and Scharping playing guard as rookies or Kalil continuing to battle injuries, at least they’re trying to address the issue.

The rebuilt offensive line is going to experience a lot of growing pains. It’s going to be better than last year, when the Texans finished 11-5 and won the AFC South despite Watson’s getting pummeled on a weekly basis. How much better remains to be seen.

If O’Brien trades Clowney, as he’s expected to do after the latter signs his franchise tender, there better be a left tackle in the deal. And a good one, because trading Clowney is going to take a toll on the defense.

Finding the kind of left tackle the Texans need isn’t worth O’Brien’s selling the house, the vacation condo and the farm, but it’s important. He has to protect the team’s most valuable asset.

Watson is now the best quarterback in the AFC South. Without Luck, the Texans are favored to win the division again, but will they be the best team?

The Texans don’t need to be reminded of what can happen when they play against Luck’s replacement, Jacoby Brissett. He’s a Texans killer.

Watson is 1-2 against the Colts with four touchdowns and two interceptions. Brissett is 3-0 against the Texans with three touchdowns and no interceptions.

Don’t write off the Colts just yet. Brissett’s got the NFL’s best offensive line. Watson doesn’t.

Protecting his most valuable commodity should be O’Brien’s No. 1 priority until the Texans develop a line that can help keep Watson upright. The Texans must avoid the same misfortune that crushed Luck and left the Colts without one of the league’s best quarterbacks at the most inopportune time of the season.

john.mcclain@chron.com

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