Five minutes into the second half on Saturday, Purdue seemed to have its game vs. Rutgers under control.

The Boilermakers led by 10 following a Jack Plummer-to-David Bell touchdown pass and had outscored the Scarlet Knights 23-7 since late in the first quarter.

But all the momentum was erased on a special-teams blunder and suddenly Purdue found itself searching for answers. It never found them in a 37-30 loss in Ross-Ade Stadium.

Following are grades:

Passing offense: C+

Through the first 35 minutes, Plummer was playing well, capping the stretch with a perfect toss to Bell in the back of the end zone for an 18-yard score to give Purdue a 30-20 lead.

But the quarterback was only 3-of-9 after that pass, with an interception, and he didn’t even attempt a throw in the fourth quarter. The pick was ugly; Plummer was pressured to roll to his right, then he tried to throw late back across the middle, a no-no.

Plummer finished 20-of-35 for 237 yards with two touchdowns and the turnover. He made some good throws, like a third-down conversion to Bell in the third quarter and another third down later when he worked through his progression before finding Rondale Moore.

Rutgers held Purdue without a pass longer than Moore’s 23-yarder and the Scarlet Knights kept the Boilermakers receiver stars from turning in huge games. Moore had 76 yards on seven receptions and Bell had 4 catches for 68 and the score.

The Boilermakers’ best offense at times was with screen passes to Zander Horvath. On those plays Horvath had 61 yards on four catches. Plummer shows great patience on the screens, waiting to suck in the defense before delivering to a teammates.

Rushing offense: B-

Purdue’s running game was great, until Jeff Brohm inexplicably abandoned it with the lead in the second half.

It made no sense.

The Boilermakers finished with 175 yards rushing and two touchdowns, but most of the yardage came in the first half — 129 — and on the first drive of the third quarter. But after Purdue took a 30-20 lead, then gave seven points back on a kickoff return, Brohm had trouble sticking with the run.

Purdue started its next drive, up 30-27, with a 6-yard rush by King Doerue, but then Brohm had Plummer throw five consecutive times, the last the interception. After falling behind on the ensuing Rutgers’ drive, Purdue took over and attempted a rush on first down, before four straight passes and a punt.

After Purdue had dominated on the ground for more than a half, Brohm just gave up on it once the game got tight again. Horvath had 101 rushing yards and a touchdown. Doerue had his best game of the season, showing off his speed to the tune of 47 yards on only six carries.

Moore picked up a key fourth-down conversion late in the first half, before Plummer scored on a sneak.

But again, Purdue just gave up on the run while it had the lead.

Overall Offense: C

Purdue was better in the red zone on Saturday, scoring touchdowns on four of its five opportunities. The one miss came in the second quarter, when Plummer tried to hit Payne Durham in the end zone on a fourth down. It fell incomplete, though Durham might have been interfered with.

The problem for the Boilermakers, though, is that the opportunities dried up by the fourth quarter. In fact, Purdue had almost no chance.

In the fourth, the Boilermakers had possession only 1:43, enough for them to gain 4 yards during a three-and-out. Otherwise Rutgers owned the ball and was able to run out the clock.

Purdue was only 4-of-11 on third downs, a reason why it couldn’t stay on the field. The Boilermakers generated 412 yards of offense, most in the first three quarters.

Passing defense: C-

Rutgers’ backup quarterbacks passed for 236 yards on 22-of-31 passing with three touchdowns and no turnovers, though Purdue came close to a pick on multiple occasions.

Purdue cornerback Simeon Smiley, who was beaten for a touchdown on Rutgers’ first possession, had an interception called off by a roughing-the-passer penalty on DaMarcus Mitchell. Smiley also dropped a sure pick.

Purdue had a couple of great individual efforts:

• Mitchell had a couple of pressures that helped the Boilermakers to hold the Scarlet Knights to a three-and-out after Purdue had taken the lead.

• Derrick Barnes, who was all over the place until he was ejected for targeting, made a simply spectacular stop when he raced to the perimeter and pulled down a Knight with a solo tackle. The fourth-down stop came a play after he nearly had a pick.

• Branson Deen blew up the right side of Rutgers’ line, swimming through two blockers on his way to a safety.

But there were bad moments, like Cory Trice getting lost in coverage in the end zone, leading to a RU touchdown. And No. 3 QB Johnny Langan’s 63-yard touchdown pass, when Kay’Ron Adams split through a confused and out-of-position defense.

Rushing defense: D

Purdue failed to contain Langan, Rutgers’ running quarterback. He had 95 rushing yards and twice scored. The Boilermakers barely had any tackles behind the line, the most significant being Lorenzo Neal’s on a third-and-goal with seven minutes left. It helped to keep Purdue down only a score.

But those plays were few. Rutgers totaled 176 yards on 52 carries.

Overall Defense: D

After another slow start, Purdue turned up the heat in the second quarter and held the Scarlet Knights scoreless on their final 4 first-half drives.

But it was short-lived. Instead, the Boilermakers gave up 37 points on the Knights’ 412 yards of offense. The guests converted 10 of their 17 third-down attempts. Purdue couldn’t get off the field, like in the fourth quarter that Rutgers dominated.

The Boilermakers couldn’t get the ball back in the fourth quarter when they needed to rally. It didn’t help them that Barnes was tossed from the game on a relatively weak targeting call. Purdue didn’t seem to be the same after.

Special teams: F

The game changed on a special teams coverage breakdown. After Purdue went up 30-20 in the third quarter, Rutgers’ Aron Cruickshank returned a kick 100 yards for the score.

And suddenly the lead was down to three. On the return, it looked as though Purdue had multiple players out of their lanes, opening a running opportunity for Cruickshank. He took advantage.

In addition, Purdue is still struggling to punt. Brooks Cormier had three chances, but averaged only 33.7 yards. Zac Collins had one for 36 yards.

Coaching: D

Brohm had an excellent first half, when he helped Purdue to a 23-13 lead at the break. Purdue had rallied from a 13-7 first-quarter deficit outscore the Scarlet Knights 16-0 in the second.

Then, after RU scored to cut the deficit to only three early in the third, Purdue responded. But after the KO return for a touchdown, it’s as if Brohm and Co. panicked. Purdue largely abandoned the run, which served as a catalyst for the lead, and it never again found its form.

And losing at home to Rutgers — a team that has improved but still only had one win coming in — in an almost must-win situation isn’t a good look.

Overall: D

Purdue lost when it — in many ways — seemed like it should have won.

And that has been a common story this season. Very disappointing.

At this point in the Boilermakers’ progression — it’s Brohm’s fourth year in West Lafayette — it seems Purdue should be farther along than to fall flat to the Scarlet Knights.