After a second punchless showing by his offense, Ohio State coach Jim Tressel is taking shots from talk-show callers and letters to the editor for his supposed conservative play-calling.

Those detractors say Tressel isn’t loosening the reins to allow the offense to do much. And their voices have grown louder since the offense hasn’t scored a touchdown in two of the last three games for the 13th-ranked Buckeyes.

Tressel didn’t do much to defend himself on Thursday, other than to say he and his coaching staff are using a bye week to try to figure out why the Buckeyes are so ineffective when they have the ball.

‘‘This is not a session hoping for a support system — you know, that we’re just fine on offense,’’ he said at a news conference. ‘‘Because we need to get better on offense. There’s no question about it.’’

He even gave additional ammunition to those who say his outdated offense is dragging down the Buckeyes (7-2, 4-1 Big Ten).

‘‘I don’t even go to a defensive meeting. I don’t even know where they meet,’’ Tressel said, half joking. ‘‘So that should tell you a little something.’’

The offense’s numbers are putrid. It doesn’t rank in the top half of the Big Ten in any major category and is dead last in passing and 10th in total offense. Among the 119 FBS teams in the nation, the Buckeyes are 44th in rushing (169 yards a game), 107th in passing (150 ypg), 95th in total offense (319 ypg) and 67th in scoring (24.6 points a game).

The eighth-year coach oversees every aspect of the offense right down to approving all play calls.

He stressed that as bad as the offense has been, he does not have any plans to put sixth-year senior Todd Boeckman back into the starting lineup at quarterback in place of freshman Terrelle Pryor. Tressel said he never considered inserting a cold Boeckman into Saturday’s 13-6 loss to No. 3 Penn State.

‘‘I didn’t have any inkling that way,’’ Tressel said.

Then, after Pryor had lost a fumble that led to the go-ahead touchdown, Tressel said he did not think of putting in Boeckman to change things up. Boeckman — who was the Big Ten’s first-team quarterback last year — is a much better passer than Pryor — who was the nation’s top quarterback recruit last spring largely because of his running ability.

Even though the Buckeyes had to go the length of the field to force overtime, Tressel stuck with the rookie.

‘‘I didn’t know what (his) fumble had to do with what we now needed to do, to come from behind,’’ he said. ‘‘I didn’t really feel that it would be a fair thing to Todd to put him out there with 1:08 to go 97 yards or 93 yards away and say, ’Sic ’em.’’’

Pryor then underthrew a pass in the final seconds that was intercepted near the goal line.

Many of Tressel’s critics say he needs to fire Jim Bollman, the line coach who also carries the nominal title of offensive coordinator, and bring in an innovative thinker who can open up the field and try some new things. Those same critics say Tressel should give autonomy to the new coordinator by staying out of the play-calling.

But Tressel emphasized he has no desire to step away from calling plays or to be anything other than a hands-on offensive coach.

‘‘I would have a hard time not having work to do,’’ he said.

The Buckeyes took Sunday and Monday off, will practice all week, and then get a 48-hour leave from Friday night until a team meeting on Sunday night. They play at Northwestern next week.

Before he began the news conference on Thursday, Tressel held up a white sheet of paper to help TV cameras set their lighting levels.

At one point, he glanced at the blank sheet of paper and cracked, ‘‘That’s my answers.’’