Boston University coach Joe Jones rubbed his chin as he glanced down at the game summary in the wake of the Terriers’ hard-fought 86-81 overtime victory against Army before 913 fans at Agganis Arena. Jones was clearly relieved that his Terriers (15-7, 8-1 Patriot League) managed to survive after wasting all of a 22-point margin before coming out on top thanks to clutch 8-of-8 free-throw shooting by senior guard D. J. Irving in the closing 1:31 of OT. Junior Malik Thomas (18 points) cemented the margin by hitting three more from the line with less than 20 seconds to play. “Basketball, ooof,” said Jones. “We played great in the first half. I was proud of the way we played, but in the second half we really struggled to guard and we did a poor job on offense. In this league, you can’t pound the ball one-on-one.” BU, which has now won the last five meetings against Army (10-10, 6-3), had trouble with the visitors on the glass in the second half. Army, which trailed 22-12 on the boards in the first 20 minutes, closed that to 43-40 by the game’s conclusion. “Too many chunks of the game we held on to the ball and we did a poor job inbounding the ball against their pressure,” Jones said. “We knew they were going to put the body on you and make it hard. They really beat us to too many rebounds in the second half. I’m just proud we were able to get it done in OT.” Irving finished as high man for the hosts with 22 points, and received help from freshman Cedric Hankerson, who posted a career-best 19 points off the bench. “I knew that Maurice (Watson) was not in the game (down the stretch), so I knew I had to be the primary ball handler and try to get the best possible shots I could make, but they kept fouling me,” said Irving. “I try not to think about foul shots too much. I know I have to make them.” To say it was a game of two halves was putting it mildly. Army came out sluggishly, fell behind quickly 9-0 and didn’t register its initial points until guard Matt Graming hit a bucket 4:14 into the game. Black Knights marksmen Kyle Wilson, who entered with a scoring average of 19.2, missed his first three attempts. Battery-mate Josh Herbeck, who was shooting .484 from beyond the arc this season, didn’t even toss up a 3-pointer. Meanwhile, BU was rolling. The Terriers opened a commanding 37-18 lead by the break and held the advantage in virtually every key category. BU, whose biggest lead of the opening half was 18 points (28-10) with 6:02 remaining, dominated in bench points (19-8), fast break points (14-4) and points off turn