The Redskins are one Trent Williams injury away from irrelevance unless they sign Eric Winston

Quick: Who’s the most irreplaceable member of the Redskins?

Hint: If you said RGIII, you’re wrong.

For my money, the one guy we could ill-afford to lose at this point is Trent Williams.

No contest.

Not that losing RGIII would be any picnic, you understand, but we’ve already seen that for a series or even a game or two, Kirk Cousins can perform like a solid NFL quarterback. Whether his game would play over an entire season is another question, but at least he’s a short-term answer.

But what happens if, God forbid, Trent Williams blows out a knee or flunks another urinalysis? According to ESPN’s most recent depth chart, Williams’ backups are, in order, Tom Compton and Xavier Nixon.

Got that? RGIII’s blind side would be protected by a former sixth-rounder out of mighty South Dakota who never suited up for a single game last season and a guy who never heard his name called in this year’s draft at all and has never been to an NFL training camp, let alone played in a real game.

If Dr. Andrews had known that, he wouldn’t have bothered with sutures when he was closing up RGIII’s knee; he’d have put in velcro to save a few steps next time.

All of which prompts me to suggest that someone in Redskinland needs to have Eric Winston on speed dial.

Yeah, I know he wants a starting job, but everyone at this point has a left tackle already. We can, however, offer him the starting right tackle job, with first crack at switching sides depending on the breaks, so to speak.

I also know Winston probably wants a fair amount of money — even though he hasn’t exactly been beating teams off with a stick up until now. And I have no idea how the Redskins could finagle a contract that size. But I suspect there’s a way it could be done.

Lastly, I’ve heard the speculation that Winston may be a bad influence in the locker room, which explains why his stay in Kansas City was a short one. I get that, too.

But he’s worth the risk, considering the other options we’re stuck with. Unlike in previous seasons, where we all conceded the Redskins weren’t one player away from Super Bowl contention, it’s hard to look at how this team finished in 2012 and the improvements they made in the draft and not predict even better things for 2013.

Assuming there are no catastrophic injuries to key personnel, that is. And no one fits that description better than Trent Williams.

Simply put, we need a backup left tackle who won’t get our franchise quarterback killed, and there just happens to be such a player on the market who played position for Kyle Shanahan in Houston.

Sign him. You’ll thank me for suggesting it one day.