LAS VEGAS — Will Dunn only had one regret after his first game as head coach of the Houston Rockets’ NBA Summer League team. After his first look at the box score, one number jumped out at him immediately.“I might’ve ran Bruce (Thornton) a little bit longer than I probably should have,” Dunn said after Houston’s 97-86 win over the Denver Nuggets on Friday. “I was like, ‘Man, I couldn’t take him off the floor.’”Thornton, for whom the Rockets traded up to acquire with the No. 31 pick in last month’s NBA Draft, played 35 minutes and finished with 27 points, three rebounds and three assists while shooting 7 of 18 from the floor and 3 of 8 from 3-point distance. The very next night, Thornton played another 32 minutes and accounted for 17 points, six rebounds and six assists while shooting 6 of 17 from the field and 3 of 6 on 3s in a 102-89 loss to the Toronto Raptors.After two appearances in a Rockets uniform, there are plenty of complimentary things to say about Thornton’s shotmaking, poise and physicality on both ends of the floor. But what Dunn said about him is the greatest compliment any coach can give a player.Thornton makes it difficult to take him off the floor.He isn’t like most rookies. Thornton started 136 regular-season games at Ohio State and left as the school’s all-time leading scorer. He’ll walk into the league more than nine months older than Rockets third-year guard Reed Sheppard. Thornton’s experience and understanding of what makes him such an effective weapon is what convinced the Rockets brass to move up in the second round and acquire him.Thornton arrived in Las Vegas with high expectations from people inside and outside of the organization, and he has managed to exceed them.