His junior season, that slow-to-heal ankle would eventually cost him his starting spot.
“I got down on myself — ‘Man, I can't do nothing,'” Alexander said.
His on-field frustration was only compounded by his off-field worry about his father. Alexander has always talked daily with his parents, but during the month or so that his dad was in the hospital, the calls became even more frequent.
“It was harder for him than for me and his little sister,” his mom said.
Harder still was the fact that none of his family was able to travel to the Cincinnati game later that week. His family, after all, has always been there. From the time Alexander started playing tee ball as a 2-year-old — any surprise that the 6-foot-4, 255-pound granite block of a man was always the big kid showing his birth certificate to prove his age? — his family has attended everything. Soccer. Basketball. Football. Track. Whatever the sport, they were there.
There were playoff games in high school when Alexander had 50 family members in the stands.
But there would always a minimum of three.
“We tell him that even if nobody else in the crowd is cheering for you, your mom, dad and sister are there,” Juanita said via telephone from Louisiana.
For much of last season, though, his dad wasn't able to be there. He missed half a dozen games as he recovered from his surgery, and even though someone from the family was at every game after Cincinnati, not having his dad around was tough.
Even though his dad made several games at the end of the season, including the Fiesta Bowl, he had a setback in April.
Another heart attack.
Slowly but surely, Alexander's dad has recovered again. The 55-year-old changed his diet, eating more whole grains and vegetables and losing 35 pounds to slim down to 205 pounds, he uses exercise bands to stay active, and he takes 17 pills a day.
He hasn't missed a game this season.
“God has allowed me to come back and watch him,” the elder Alexander said of his son. “All of these things are blessings that I don't take lightly.”
Neither does the younger Alexander.
“He could've died,” he said. “He was having minor heart attacks as he was driving back from the game. Then, he had my mom, my sister and other family members in the car with him.
“That's why I feel everything has just been a blessing. Everything that's going on right now ... I just feel like I'm being blessed.”
This season has brought the kind of success that his parents prayed he would have. Alexander has been terrorizing offenses since the start — he leads the Sooners in tackles for loss, sacks and quarterback hurries heading into Saturday's game at Kansas — but what they witnessed against Texas left them with tears in their eyes.
Juanita came down by the field after the game, pulled her son into a hug and refused to let go.
“I'm so proud of you,” she said.
His dad feels the same way. He was still riding the emotional high of Saturday's game two days later.
“Every week, he seems to be getting better, a little more forceful, a little more focused,” said the father on the mend of the son on the rise.
“It can't get any better, to tell you the truth.”