Matt Glass and Tyrell Lynch are too old at this point to grow any taller.

But they’re also too young to be relied upon to solve all the problems of the undersized and undermanned Massachusetts men’s basketball team.

With the way Tony Gaffney keeps playing, they may not have to. But his heroics on both ends of the floor fell one-point short Monday night in a 75-74 home opening loss to Jacksonville State at the Mullins Center.

“Right now Tony is the only one playing with leadership,” senior point guard Chris Lowe said after the game. “Just because I had [20] points that doesn’t mean anything. I’m not providing as much leadership as I should, and if I don’t do that the team is not going to be successful. Everything is really falling on me.”

With 7-footer Luke Bonner and reserve forward Matt Hill out with injuries, it also falls on the underclassmen to step up their performances. But even with a fully healthy roster, rebounding and toughness inside was a major question mark this season.

Gaffney takes care of a lot of that by himself, but even though he played all but 1 minute Monday night in a strong all-around performance, he can’t shore up the center and forward positions at the same time.

That leaves sophomore Matt Glass (6-foot-6) and freshmen Tyrell Lynch (6-foot-9) and Travon Wilcher (6-foot-7) in charge of keeping opposing offenses out of the paint and off the glass.

And no one could do that against JSU’s Jonathan Toles on a drive to the hoop with 9 seconds remaining for the game-winning layup.

“I’m trying like heck,” said UMass coach Derek Kellogg, referring to trying to get his team to play harder and with more fire. “My whole speech before, after and during the game is to play intense basketball for 40 minutes.”

Kellogg admits that it’s tough to rely on young players such as Glass, Lynch and Wilcher down-low at this stage of their careers, but he really doesn’t have much of a choice right now.

“We played some strange, strange lineups tonight and that’s who we have on our roster,” Kellogg said. “And so I’m just going to try to play guys who are going to help us win and guys that will make plays defensively.”

Gaffney made plays all night and in every possible way – scoring 20 points, grabbing 13 rebounds and blocking eight shots in a near triple-double. Lynch was solid early on, grabbing five rebounds and scoring six points on easy baskets in the paint. But he made no impact in the second half, registering a single rebound in 6 minutes.

With guards Chris Lowe, Ricky Harris and Anthony Gurley constantly on the floor – often all at the same time – that leaves three non-rebounders and interior defenders on the court. That enabled the Gamecocks to score 32 points in the paint, capped by the final basket of the game by Toles.

Kellogg talked after the game about how hard it is for his team to play with the intensity required on defense for the Minutemen to be successful.

“The second your guy catches the ball, you’re on him. And you’re covering a guy for all 35 seconds of the shot clock and then you run up the court and attack on defense, only to sprint back on defense,” Kellogg said.

“And you never stop,” he added. “Working that way is a hard thing to get across. It’s hard to do when you really only have nine, 10 guys. Maybe I’m asking too much, but I don’t think I am.”

Kellogg is concerned that his team isn’t taking enough pride on defense and is focusing too much on their offense.

“The thing I want to get our guys away from is not get excited when you make shots, let’s get excited when you make a stop on defense,” he said. “I think the floor is a little tilted right now where they run a little faster one way and not so fast the other day and we’re trying to change that everyday.”

They’ll have to in order to compete in a deep Atlantic 10 this season.

Eli Rosenswaike can be reached at [email protected].