Blaine Gabbert took over as Tennessee's starter for the last two games while Mariota dealt with a nerve issue in his elbow that resulted in numbness and tingling in his right hand.
Gabbert suffered a concussion in the Titans' 9-6 win over the Jacksonville Jaguars, though, which pressed Mariota to resume his regular duties under center. He finished the game 12-of-18 for 100 yards.
Mariota's numbers illustrate the fact he was less than 100 percent in Week 3 and that the Titans had to work around that. Vrabel said that shouldn't be the case against Philadelphia, per the Tennessean's Joe Rexrode:
Gabbert's concussion added even more urgency to Mariota's recovery because Austin Davis would be the next man up if Mariota were unavailable. The Titans announced Tuesday they signed Davis and added him to the 53-man roster.
Davis hasn't started a regular-season game since the final week of 2015, so going with him against the defending Super Bowl champions would be a recipe for disaster.