Defending a Super Bowl title isn’t supposed to be fun, and Giants coach Tom Coughlin served as a harsh reminder of that in his conference call with the media following his team’s 32-31 preseason loss to the Jacksonville Jaguars.

“We have no illusion about the improvement that needs to be made,” Coughlin said on Saturday, the day after his team muffed two punts and yielded two touchdown drives of over 80 yards apiece. “I'm talking from the top of our team to the bottom.”

Yes, there were bright spots. Coughlin described first-round pick David Wilson as a “plus” after seeing the rookie total 43 yards on seven carries, 26 yards on two receptions and 76 yards on a pair of kickoff returns.

“He showed us some things we can depend on going forward,” Coughlin said.

The Giants backup defensive linemen had six sacks, and the receivers/tight ends played well, particularly in the red zone (three touchdown receptions).

But Coughlin can’t whitewash his first-team defense’s performance.

Jacksonville quarterback Blaine Gabbert picked apart New York’s secondary on an 89-yard first-quarter drive that ended with an easy touchdown pass over cornerback Prince Amukamara.

“I was disappointed by the 89-yard drive,” Coughlin said. “Our defensive players would be the first ones to come forward and say they’re disappointed as well.

“I was disappointed when [Amukamara] got beat on a long pass. He was playing outside end on man coverage and got beat to the outside.”

But the starters weren’t the only ones taking heat.

Despite Wilson’s impressive performance and the fact that second-round pick Rueben Randle had a nice touchdown reception, Coughlin couldn’t help but list the things the Giants failed to accomplish.

“Pass protection, once we got into the depth of our team, wasn't very good," Coughlin said. "There are things back and forth; I didn't like our time of possession being only at about 26 minutes, which bothers me as well.”

As for the bizarre ending to Friday’s game, Coughlin didn’t have much of a reaction. The replacement officials called third-string quarterback Ryan Perrilloux for being over the line of scrimmage on his final throw -- and seemingly failed to do a 10-second runoff afterward, which would have ended the game. The Giants were allowed one final play -- perhaps one more than they should have been given -- but Perrilloux was sacked, and the mistake won’t be haunting the officiating crew.

“There was an explanation,” said Coughlin, who insists the replacement officials are doing the best they can. “I can’t tell you what it was at this time because to get another snap was all I was concerned with. At that point in the game there was not time for a lengthy explanation. The only thing we knew was the ball was brought back. They said something about 10-second runoff, but it didn’t take place.”

Apparently the Giants aren’t the only ones with room for improvement.

Notes: Coughlin said WR Domenik Hixon (hamstring) was kept out of the game for precautionary reasons. … There were no major injuries to report on Saturday.

Follow the Giants and Alex Raskin @CBSSportsNFLNYG and @AlexRaskinNYC.