KNOXVILLE - They can be the result of position switches, early arrivals or sudden realizations of talent or even come out of nowhere.
But however spring surprises occur in college football, they happen every year on practice fields all across the country. If and how those players continue their improvement and development is always the catch.
The Times Free Press makes its picks for Tennessee's three biggest spring surprises and looks at the prospects for each moving forward.
1. Alex Bullard, sophomore offensive lineman
Nobody really knew what to expect from the former Brentwood Academy star when he transferred from Notre Dame to UT in January, but it didn't take long for the 6-foot-2, 309-pound Bullard to make an impact.
"He's been an incredibly big surprise," Vols coach Derek Dooley said after the spring's fourth workout.
The former four-star prospect worked at center and tackle this spring and took over a first-team spot at right tackle when Ja'Wuan James couldn't practice because of mononucleosis. That versatility will make him a valuable asset on a thin offensive line.
"He brings an attitude to the offensive line that you want to see," defensive end Willie Bohannon said. "You want to see somebody getting after this defensive lineman that's been trying to kill our quarterback the whole time and pancake him down the field. You want to see things like that, and he's been pretty good."
Bullard, whose father died last year, is still awaiting a ruling from the NCAA on a hardship waiver that would allow him to play the 2011 season.
"Alex was a surprise just because he landed on our program and we didn't know much about him," Dooley said. "He really just played great. He's going to really help us."
2. Daniel Hood, sophomore defensive tackle
After a redshirt year and a season as a backup offensive lineman, Hood met with the coaching staff and suggested a move to defense. But even the 300-pound Kingsport native and Knoxville Catholic High School star was surprised at his rapid ascent to a first-team spot at nose tackle.
"It was more I'd like to be here, but expect it? No," he admitted Saturday. "You've got guys like Malik [Jackson], Montori [Hughes] and some of our other D-tackles that we've got.
"I think just the fact that I love contact, I love hitting somebody, and fighting two people instead of just fighting is more of a boost to your ego a little bit. When you're playing James Stone and Zach Fulton hitting you at the same time and you're able not give up any ground and still come off and sometimes make a play, it feels pretty good."
The Vols liked Hood's size in the middle of the defensive line, and though he'll have to fend off junior college tackle Maurice Couch, Hood has likely claimed a spot in the rotation.
"I've been really pleased and surprised with Daniel Hood," defensive line coach Lance Thompson said. "He's got a role, he's worked hard for it and he's a tough guy."
3. Justin Coleman, freshman cornerback
Given his size (5-10, 185) and ability (a four-star recruit per Rivals.com), Coleman's excellent spring isn't totally shocking. But it's worth noting any time a player who's supposed to be finishing his senior year of high school comes in and immediately makes an impact, and the Vols had three such players in Marcus Jackson (co-starter at left guard), Vincent Dallas (second-string receiver) and Brendan Downs (second tight end).
Coleman, though, came into a position that returned everyone from last season. the Brunswick (Ga.) High School product made his mark in Saturday's spring game, fending off a pair of passes intended for the taller Justin Hunter on end-zone fade patterns.
"They went right at Coleman, and he went up there and covered Hunter," Dooley said. "Nobody told him Hunter was a good player. He's a competitor; that's what I loved about him. You know those guys in high school that play everything and do everything? That was him. It just says something about their competitive nature."
Coleman, who left spring bracketed as a starting cornerback with Anthony Anderson, will be in a competitive battle for playing time when possibly seven more defensive backs arrive in June. But his head start should help his efforts to hold on to a rotation spot.
"I think Justin is going to be a good solid player," Dooley said. "He's tough, he's physical, he's still light right now and he doesn't know the difference between Cover 2 and Cover 3. But that's OK. He'll get that. He's got the right kind of intangibles and he's instinctive."