TAMPA — Kwon Alexander used to pack his suitcase on Monday for the weekend road trip as a linebacker at LSU. He entered the NFL draft as a 20-year-old. After one preseason game, he was promoted to the Bucs' starting defense.So being ahead of schedule is something that has come naturally to Alexander."He plays very fast," general manager Jason Licht said. "He's a very serious guy. He loves football. He mentioned in one of our interviews how he prepares. He's very diligent about everything. … He's all business. That's what this football team needs."On Tuesday, in an early team drill, Alexander emerged from the bottom of a pile with a fumble recovery. That kind of aggressive playmaking has enabled him to replace veteran Bruce Carter as the starting middle linebacker after an impressive performance in the Bucs' 26-16 preseason loss Saturday at Minnesota."He's there because we feel he can make plays like that," coach Lovie Smith said. "He's warranted some time in this role, in this position. I think every day, you're going to see him do something better. He has big-play ability like that. And he still strikes you, and that's what he's supposed to do."Carter, a Cowboys free agent who had five interceptions last season, began taking reps Tuesday at strongside linebacker with Danny Lansanah. Carter recognized Alexander's precocious talent shortly after he arrived as a fourth-round draft pick."The kid has got an incredible motor," Carter said of Alexander. "He's running all day. He's very smart and intelligent as a player, and I don't think he's had any setbacks since he's come in. He's done an awesome job."Alexander admits he is playing with a chip on his shoulder. After being a first-team All-SEC linebacker, he didn't expect to last until the draft's fourth round."I think I had a pretty good year and I was just ready to go and pursue my dreams," Alexander said. "I felt I could get better in the NFL and learn more. And now the time is here."It's been crazy. It's a big move when you get to the NFL. But I'm working. I'm learning. I've still got a long ways to go. But I'm doing everything I can do. I make some little mistakes, but that's going to happen. I'm just trying to do better."It remains to be seen whether the Bucs will trust Alexander to call the defense as middle linebackers typically do under Smith."Just look at our history with (middle) linebackers," Smith said. "Any good defense starts there. He's the quarterback of our defense."Three years ago, the Bucs entrusted Lavonte David to make all the defensive calls as a rookie despite playing weakside linebacker. "When they let me wear the green dot on my helmet (denoting the helmet communicator), I realized if they trust me to call the whole defense, I could do something special in this game," Davis said.Defensive tackle Gerald McCoy said Alexander reminds him of David as far as speed and aggressiveness."I told him the other day, in 2012 we were in the spring and we were watching film, and I kept seeing this guy go fyew, fyew ," McCoy said. "Who is this kid? I started calling this kid 'The Flash.' It ended up being Lavonte David. I told (Alexander) I haven't seen nobody run like that since when Lavonte first got here. He loves the game. He's doing all the right things to be where he's at. He's rightfully earned his opportunity to be with the ones (starters). When you talk about getting downhill or getting to the ball, he's at the top of the list."Alexander, who was the No. 2- rated high school player in Alabama (Jameis Winston was No. 1), is also fortunate to play for a coach who doesn't mind starting rookies in key spots."We all would prefer a veteran," Smith said. "But I prefer the best player. And a lot of times, he's young. It seems like more and more they're younger. I have no problem, and history shows that, playing young players. And for guys coming in, we let them know that early on. This is what our history says. If you're the best guy, it doesn't matter whether you're a rookie or whatever, we'll play you right away."And they know Alexander will never be caught unprepared. Contact Rick Stroud at firstname.lastname@example.org and listen from 6 to 9 a.m. weekdays on WDAE-AM 620. View his blog at tampabay.com/blogs/bucs. Follow @NFLStroud .