Maryland sophomore forward Alyssa Thomas was named ACC player of the year. (John Amis/Associated Press)

Alyssa Thomas, along with thousands of others, watched over and again as her brother shattered the backboard. The video of Devin Thomas’s violent dunk in a Pennsylvania high school basketball game two weeks ago was going viral on the Internet, and soon ESPN had promoted it to first among the top 10 plays on “SportsCenter.”

For big sis, this just wasn’t going to work. Not for hyper-competitive Alyssa Thomas, the Maryland sophomore forward who on Thursday was named ACC women’s basketball player of the year.

Thomas is the last person you’d want to be around after she lost or became an afterthought in anything, much less to a family member. That spirit comes from Tina Klotzbeecher-Thomas, her mother, who practically demanded her eldest daughter take up basketball at age 5 and gave no quarter even when they played Candy Land.

“She’s the biggest sore loser I know,” Devin said of Alyssa.

So with both mother and brother in attendance at Comcast Center several days later, Thomas did something about it. Saving her flair for the dramatic until the last possible second, Thomas blocked a shot as time expired to preserve a 63-61 victory over No. 5 Duke that was the most gratifying this season for sixth-ranked Maryland.

Later that night, what’s simply called “the Block” in and around College Park began circulating on ESPN’s top plays, vaulting all the way to No. 1. Then, in the top plays of the entire week, “the Block” surpassed the dunk. As usual, Thomas had gotten over on her brother.

“You should see when it comes to the holidays when we play cards at our house,” she said. “It’s pretty crazy in there.”

Said Maryland Coach Brenda Frese: “I’d put her up there as one of the most competitive players I’ve ever coached. Her will to win and do whatever it takes is just off the charts.”

Thomas’s block against the Blue Devils, for instance, concluded a game in which the agile forward had missed 9 of 11 shots and committed five of Maryland’s 19 turnovers. Earlier this week, as the sixth-ranked Terrapins prepared for their ACC tournament quarterfinal on Friday night, Thomas referenced that play as a defining moment in large part because she’s not acclaimed for defense.

It’s a pardonable oversight, though, in light of how in less than two full seasons Thomas has gone from promising freshman to ACC leading scorer to the second sophomore in ACC history to be named player of the year, joining former Washington Mystics guard Alana Beard. Her uncanny knack for closing also has been a bane to opponents as well as an inspiration to teammates.

“I see everything,” second-team all-ACC junior forward Tianna Hawkins said of Thomas’s many highlights. “We just wait until after the game to say, ‘Dang Alys, how’d you do that?’ ”

Just ask No. 15 Georgia Tech, which twice absorbed the best from Thomas and had no counterattack. In the first meeting on Jan. 6, Thomas sank the go-ahead jumper and bonus free throw with 17 seconds remaining in a 77-74 victory during which Maryland erased a 20-point deficit.

Then, a month later, Thomas had 23 points and 12 rebounds in a 64-56 road win as significant as any this season. With a sweep of the series, the Terrapins (25-4, 12-4) claimed the tiebreaker and thus the No. 3 seed in the ACC tournament despite finishing even with Georgia Tech in the conference.

“She’s grown tremendously,” Hawkins said. “She’s added the defensive side to her game. She’s not all offense, so it’s great to see her continue to improve her game, being that she works hard every day.”

Lest anyone forget Thomas’s versatility, it was on prominent display over the final two games of the regular season. In an 84-64 throttling of North Carolina last Friday, Thomas finished three assists short of a triple-double, and during Sunday’s season finale at North Carolina State, she had 24 points and a career-high 17 rebounds.

Twenty-two of those points came in the second half, when she scored 16 in a row.

Thomas was the only Terrapins player to score over 101 / 2 minutes in the second half, and she added four blocks and three steals.

“That’s something my mom really focused on,” said Thomas, who is averaging 17 points per game this season. “I wasn’t the tallest growing up, but my mom knew I would grow. Didn’t know how tall I would be, so she always put me at every position just to be a complete player and get a little bit of everything.”

Thomas topped out at 6 feet 2, and when Frese first scouted her prized recruit from Harrisburg, Pa., during a tournament in Baltimore in summer 2008, infatuation immediately took hold. Frese recalled how dazzling Thomas was to watch as she acquitted herself with the clout of a power forward and the agility of a point guard.

Among Frese’s favorite yarns is how she was torn between making that drive to Charm City or traveling to Argentina, where some of the country’s elite high school players were playing for USA Basketball.

“I had heard phenomenal things about her, and I chose to stay home,” Frese said. “Obviously well worth it.”