Gibson injured his calf during Sunday's game against the Chiefs, Doug Kyed of Pro Football Focus reports.
Gibson was examined for a shin injury early in the contest but was able to return to action. Now, he's again being looked at by Washington trainers, only this time a calf issue is to blame. If he's unable to get back on the field, Gibson will finish Week 6 with 12 touches for 44 total yards. In Gibson's stead, J.D. McKissic will be the prime beneficiary, though undrafted rookie Jaret Patterson could get some run, too.