Texas RB Malcolm Brown entering NFL Scouting Combine with chip on his shoulder

When Texas Longhorns running back Malcolm Brown signed with the Horns as a heralded five-star prospect out of Cibolo Steele in the 2011 recruiting class as the No. 13 player overall and the No. 3 running back, the script didn't look like this.

Not after rushing for 2,637 yards and 33 touchdowns as a senior in leading his school to a state title.

Not after doing this on national television against Steele's rival, San Antonio Madison:

No, the script didn't look like this. Not even close.

It didn't feature a promising freshman season derailed by an foot injury that caused Brown to miss two games and finish slowly. It didn't feature a sophomore season derailed by a high ankle sprain that caused him to miss five games and finish slowly.

As a junior in 2013, even the best season for a Texas running back in total rushing yardage since Jamaal Charles in 2007 (904 yards) wasn't enough to live up to the lofty expectations that accompanied him the 61.7 miles up I-35 from Byron Steele II High School.

The script certainly didn't feature Brown playing behind a completely inexperienced offensive line in 2014, though he was able to make the best of it by once again leading the team in rushing yardage with 708 yards and six touchdowns.

"The career at Texas wasn't what I hoped it to be," Brown told the Fort Worth Star-Telegram after a workout at the Michael Johnson Performance and Athletic Center. "But you've got to keep grinding and keep your faith. That's what I plan on doing."

Now all that Brown can do is tell a different tale through his athletic testing at the 2015 NFL Scouting Combine, where he'll have to answer questions about his explosiveness after his 40-yard scamper against Oregon in the 2013 Alamo Bowl stood as his only career run of more than 31 yards. In fact, Brown took only three total carries over 30 yards in his time in Austin.

After spending six weeks training under Johnson, Brown believes that he's yet to show his true abilities.

"I feel like there's still a lot to show," Brown said. "I kind of have a chip on my shoulder. I want to prove something to some people and show that I can play."

Of the six drills he will perform this week, none looms as large as the 40-yard dash and Brown knows it -- that's why he was training with Johnson.

"Something that I really came here for was to work on my 40 [-yard dash]," Brown said. "I feel if teams see me run a good 40, that'll open some eyes a little bit. Just from what I've heard, a lot of teams don't think I [have breakaway speed], so it's something I wanted to come here and improve upon."

To prove to NFL teams that he has enough juice to run away from defensive backs at the next level, Brown may have to break the 4.60-second mark. He left high school with a reported 4.44 40-yard dash that sounded bogus by the time he signed and rings even more hollow now, although he did help the Steele 4x200m team qualify for state as a sophomore.

But just how high are the stakes?

Brown may need a strong Combine showing to merely hear his name called in the draft:

Brown looks the part, boasting a combination of power and balance to keep his feet and drive through contact for additional yardage. Unfortunately, he lacks the wiggle and breakaway speed that teams value in today's NFL, leaving the former five-star recruit hoping just to get drafted.

WalterFootball.com ranks Brown No. 21 at his position and grades him between the sixth round and going undrafted.

So that chip on Brown's shoulder better not slow him down when he runs the 40 on Saturday, because otherwise he'll have to make a roster the hard way.

The script didn't look like that, either.