Note: Because I tried to focus on specific players, none of the offensive line or the defensive tackle position battle were listed.
1) Connor Wood, quarterback
Sure, it's tempting to put Garrett Gilbert here, but he's somewhat irrelevant for spring game performances. Barring immense improvements, you know pretty much what you're getting from him. And that makes Gilbert's competition the most important person to watch. The spring game should give us some idea of Wood's progress and whether he'll have enough to pass Gilbert through fall practice. Whoever does win the job will have the luxury of superior weapons to what Gilbert played with a year ago.
2) Cody Johnson, fullback
Johnson has played a number of roles in the backfield this spring, but arguably none as important as his transition to fullback. Johnson is an ideal player for the position, a tank who craves contact and has great athleticism for his size. He projects as arguably the top fullback in the 2012 NFL Draft. And fullback is a key position in Texas's new offense, which uses the fullback as a lead blocker, a man in motion and as a receiver. Johnson also figures to receive work as a single back at times, especially in short yardage situations. Fullback is an underrated position, and if Johnson plays to his potential there, he could drastically improve the offense.
3) Adrian Phillips, cornerback
First, the Longhorns lost their top three cornerbacks from a year ago. Then Eryon Barnett, one of the top returning players at the position suffered a season-ending injury. That forced the coaching staff to move Phillips and Bryant Jackson from safety to cornerback to promote depth. Phillips, by all accounts, has done more than that, with some promoting the savvy sophomore as the team's top cornerback. Here's what we know for sure: Phillips has outstanding ball skills, ones developed by his time at wide receiver. And he has the skill set to play any position in the secondary, though he arguably projects best as a ball-hawking safety. But if Phillips can turn into a legitimate No. 1 cornerback, that would go a long way toward building a strong secondary.
4) Kenny Vaccaro, safety
The other move that would help would be the promotion of Vaccaro to the starting lineup. Simply put: Vaccaro runs better than the other safety candidates, and was compared to a bag full of rattlesnakes by defensive coordinator Manny Diaz. Former defensive coordinator and current Florida coach Will Muschamp once said Vaccaro "had thump to him." Those are different ways to say the same thing: Vaccaro is a nasty hitter, and somebody who lends both athleticism and attitude to a defense. If he starts, he'll be an All-Big 12 candidate.
5) Reggie Wilson, defensive end
Wilson looked fantastic in open practices early last fall, and has earned rave reviews this spring for being able to get after the passer. If Wilson is as advertised, the Longhorns will have some options when it comes to pressuring the quarterback on passing downs. Defensive end Alex Okafor is more of a strong-side end and can bump inside to give the Longhorns more interior pass rush punch. If he does that, Texas will need another outside pass rusher to pair with end Jackson Jeffcoat. Wilson's ability to get after the quarterback could be huge against a typically pass-happy Big 12 slate.