TORONTO — It has turned into a really bad habit that may cost the Dallas Mavericks dearly somewhere down the road.Even with Dirk Nowitzki getting a day off to rest, the Mavs led the Toronto Raptors by 21 points late in the first quarter Wednesday night at the Air Canada Centre. But as they have too many times this season, the Mavs coughed up that large lead and wound up getting embarrassed again during a 93-85 loss to the Raptors.It was the fifth time the Mavs (25-19) lost a game this season after holding a lead of at least 17 points. And now they’re doing it in another country.The Mavs built a 19-point lead at home against Toronto on Dec. 20 and then lost to the Raptors 109-108 in overtime. Now this.And just like other times during a topsy-turvy season, the loss was downright inexcusable. And the Mavs know it as the Raptors (21-20) ended the game on a blistering 20-7 run.“We played two good quarters, and they played three good quarters. And it’s a 48-minute game, and we’ve got to do it for four quarters,” coach Rick Carlisle said. “I believe in our team and I believe in these guys, and we’re going to keep working at it. … I know we’re capable.”The Mavs started off like they were capable. With ex-Raptor Jose Calderon scoring 10 points, the Mavs busted out of the gate with a 34-13 lead late in the first quarter.But as been their trend throughout the season, the Mavs couldn’t stand prosperity and started throwing the ball all over the place except where it needed to be thrown. Dallas’ defense also went on vacation, and its offense took a siesta, too.The loss was so devastating that forward Shawn Marion didn’t care to make a comment afterward. But guard Devin Harris did.“We kind of took our foot off the pedal a little bit and allowed them to get back in the game, and after that, it was kind of a dogfight,” Harris said. “We’re having great starts, but we’ve been struggling to sustain it. … It doesn’t take long for NBA teams to make runs, and obviously their bench came in with a lot of energy and got them back in the game.”The Mavs were outscored 31-17 in the second quarter and 25-12 in the fourth quarter.“It’s very frustrating,” said ex-Raptor Vince Carter, who absorbed a mixture of cheers and boos constantly during the game. “I think we just have to zero in on just staying focused, staying the course, continue to do what got us to that point. I think sometimes you get comfortable. It’s very frustrating.”After trailing 51-46 at the half and 73-68 after three quarters, the Raptors finally went ahead 82-81 following a bucket by Jonas Valanciunas with 4:35 left.A 3-point field goal by Amir Johnson pushed the Raptors’ lead to 88-84. Johnson later added a dunk, and DeMar DeRozan finished off his career-high 40-point night with a steal and a dunk to put Toronto up 92-85 with 1:48 to go.Still, the Mavs, who committed 21 turnovers that led to 25 points for Toronto, know they never should have been in a scrum fighting for a win down the stretch.“This is the year of ‘No lead is too big, no deficit too great,’ ” Carlisle said. “You’re seeing big leads disappear all the time, and we’ve got to be better because they’re hard to get.”To their credit, the Mavs have been getting those big leads most of this season. Keeping them — that’s another story.
Dwain Price, 817-390-7760 Twitter: @dwainprice