For Washington Redskins Coach Mike Shanahan and his son Kyle, the team’s offensive coordinator, it’s suddenly all about John Beck.

Who would’ve guessed that one of pro football’s most respected coaches and one of the game’s up-and-coming young assistants would tie their fortunes — and those of the Redskins — so closely to a journeyman quarterback who hasn’t started a game since 2007?

But that’s what they’ve just done.

Mike Shanahan’s announcement Wednesday that Beck, not error-prone Rex Grossman, would start against the Carolina Panthers on Sunday was unavoidable. Grossman sealed his fate after four of his passes were intercepted during last weekend’s loss to the Philadelphia Eagles, and Beck provided something of a spark in relief.

Now that the Shanahans have acknowledged they were wrong in naming Grossman the starter six weeks ago, however, they must be right this time about Beck.

Since he was brought to Washington by owner Daniel Snyder before last season and given the task of reviving the Redskins’ fortunes, Mike Shanahan has improved the team. The Redskins are better at nearly every position than they were before last season except one — quarterback. It’s only the most important position on the field.

If Shanahan and his son are wrong about Beck — as they were about Donovan McNabb last year and Grossman this year — they would be 0 for 3 in picking people for the position they supposedly know so well. They would undermine whatever improvements they’ve made to the roster elsewhere. And they would set back the franchise’s progress a year or two or maybe more, because if the Redskins enter next season without a proven starting quarterback they would be right back where they were when the Shanahans arrived. It’s really that simple.

It seems like it was only yesterday that Mike Shanahan stood at a lectern, comparing the newly acquired McNabb favorably to Hall of Fame quarterback John Elway, who led the Shanahan-coached Denver Broncos to two Super Bowls in the late 1990s.

Shanahan benched McNabb for the final three games last season, then traded him to the Minnesota Vikings last summer. McNabb has lost his starting job again, just six games into this season with the Vikings.

Shanahan did it again the other day, mentioning Elway’s interception problems in Denver in offering support for Grossman. (Beck had better hope Shanahan doesn’t link him to Elway too, because those comparisons have only been trouble for Redskins quarterbacks.)

The Shanahans’ quarterback missteps began even before their costly McNabb blunder. They go back to their decision to dump Jason Campbell, the incumbent starting quarterback when they arrived in Washington. They traded him to Oakland before giving him an opportunity similar to that which Grossman received and Beck is about to get.

Campbell’s critics contend he needed to move on, that he had his chance with the Redskins and just didn’t cut it, and that it was best for Campbell and the team to part.

Even on his worst day, though, Campbell wouldn’t have been as bad as Grossman has been for much of this season. You have to ask yourself, where would the Redskins be if the Shanahans had kept Campbell and maybe helped him improve under their tutelage? Campbell was playing well with his new team, the Oakland Raiders, until suffering a broken collarbone last Sunday.

“The first year when I came here, I had to make a decision with Jason Campbell or Donovan McNabb. I went with Donovan. Took a shot,” Mike Shanahan said Wednesday. “There wasn’t a whole lot out there at that time — not a lot of decisions to be made.

“Obviously, that didn’t work out. But I wasn’t going to keep him [McNabb] here for three or four years. You make a decision if he’s a guy of your future. He wasn’t, so we went with Rex.”

Now Shanahan has closed the Grossman chapter in Redskins history too. It was time. Although he finally gave Grossman the hook after the four-turnover debacle against the Eagles, it could have occurred earlier this season. But after blowing it as badly as he did with McNabb, Shanahan was staking his reputation on Grossman and hoping he would make him look good. Didn’t work out so well.

So now he and his son are staking their reputations on Beck. They have no choice. They have to provide Beck with at least as much time as Grossman received to ultimately reaffirm what most people not named Shanahan already knew: Grossman wasn’t the guy.

Mike has reached his position because of his expertise on offense and success in Denver. Kyle was widely considered a rising star — a potential future head coach. Repeated poor decisions, however, can ruin reputations.

The Shanahans have shifted gears again by going with Beck. Maybe they finally have it right. If they don’t, Snyder may be asking them bigger questions than about who’s starting at quarterback.