Bill Callahan is expected to return to the Redskins for another season, taking care of one major question regarding Jay Gruden's staff.

Washington's offensive line coach of four years should be back for 2019, Bruce Allen told reporters at the Senior Bowl in Mobile, Alabama.

Bruce Allen says Jim Tomsula isn’t under contract but Bill Callahan is under contract and should be back. Jay Gruden is working on the coaching staff. — JP Finlay (@JPFinlayNBCS) January 22, 2019

There had previously been much speculation that Callahan was on the outs.

Callahan came to D.C. in 2015 and has long been hailed as one of the league's top O-line gurus. His tenure with the Redskins has featured both positives and negatives.

Among the positives? Brandon Scherff has grown into an elite NFL guard, Morgan Moses earned a pricey contract extension and 2017 sixth-round pick Chase Roullier spent all of last year as the offense's starting center. And Trent Williams, of course, is still Trent Williams.

However, the unit has been decimated by injuries the past two seasons. Some wonder if Callahan's intense coaching — often times, he keeps his players for an extra 30 minutes after weekly practices — has something to do with it.

In addition, the Burgundy and Gold's running game has never really emerged as a dominant one for a 16-game schedule, and Callahan has always had a large role in that area.

Allen said Gruden's full complement of coaches will be finalized in a few weeks. The head coach wasn't at the Senior Bowl on Tuesday; instead, he was conducting interviews at the Redskins' Ashburn facility.

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