Fisher, a 6-3, 270-pound sophomore from Nashville, saw backup action at tackle last weekend against Memphis and performed adequately.
"Walter's doing a good job," head coach Phillip Fulmer said. "In trying to get five ends and five tackles that can play in the ball game that was our best opportunity. But he's got a lot to learn."
Fisher was a defensive end in junior college and projected to play there for Tennessee. He's a tad undersized for tackle but, like the 6-4, 275-pound McBride, he can offset his lack of heft with quickness.
"He's a fast defensive tackle," Fulmer said of Fisher, "and he's an average-speed defensive end. He told me the other morning that he really liked it in there (tackle) and felt good in there. He can match up real well."
Defensive coordinator John Chavis also likes what he has seen of Fisher at tackle.
"He's coming on," Chavis said. "We've got to have some depth there, and he's a guy we feel like can give us some help. He's not your 300-pound guy but he's got some real quickness, so we're excited about that."
Fisher's switch to tackle left Tennessee short-handed at end, so Nelson has been moved back outside.
"We're trying to rob Peter to pay Paul," Chavis said. "We're trying to get the best combination we can. Chase might eventually be back inside because he's going to end up being a pretty good-sized player before it's all over with. But right now, with what we're trying to get done, he's better suited to help us outside."