With the Steelers stuck in their first four-game losing streak since 2003 and their chances of making the playoffs in danger of flat lining, Tomlin said significant changes could be coming for the defending Super Bowl champions.

"Certainly, I think it's appropriate we give some guys an opportunity and see if they can play," Tomlin said yesterday at the Steelers' South Side facility. "To what extent changes will be made, I think it's premature, but obviously that's taking place. We're going to be aggressive in terms of looking at potential changes in not only what we do schematically, but who we have do it in all three phases because it is appropriate."

The secondary could be most affected by a late-season shakeup.

Fourth-quarter

folly

The Steelers are

yielding 297.3 yards per

game, but 105.1 of those have come in the fourth quarter. Here is a

breakdown of the yards and points the Steelers have allowed in the

fourth quarter this season:

Yards

Points

Result

Titans

51

3

W, 13-10 (OT)

Bears

113

10

L, 17-14

Bengals

139

14

L, 23-20

*Chargers

81

21

W, 38-28

Lions

95

7

W, 28-20

Browns

51

0

W, 27-14

**Vikings

210

7

W, 27-17

Broncos

20

0

W, 28-10

Bengals

80

6

L, 18-12

Chiefs

96

7

L, 27-24 (OT)

Ravens

102

3

L, 20-17 (OT)

Raiders

223

21

L, 27-24

*Fumble recovery

returned for a touchdown

**Kickoff

returned for a touchdown

Tomlin's background is as a defensive backs coach, and the back line of the Steelers' defense faltered badly in a 27-24 loss Sunday to the Oakland Raiders.

Bruce Gradkowski burned the Steelers for three touchdown passes in the fourth quarter, and the Seton-La Salle High graduate rallied the Raiders from three deficits in the final 15 minutes at Heinz Field.

The loss continued a disturbing trend in which a unit that ranks fifth in the NFL in total defense (297.3 yards per game) has been unable to close out games. The Steelers already have allowed more points through 12 games this season (231) than during the entire 2008 regular season (223).

In five of their six losses, the Steelers (6-6) had the lead in the fourth quarter.

Points parade

Here is a look at

the points the Steelers have

allowed per quarter this season, compared to 2008, when they allowed

223 points through 16 games:

Year

Quarters

Total

2009

32-48-46-99-6

231

2008

54-65-29-75-0

223

They will almost certainly have one new defensive starter Thursday night against the Cleveland Browns, as cornerback Joe Burnett will play in place of William Gay, who may be unavailable after sustaining a concussion Sunday.

Even if Gay is cleared to play -- he will take a battery of neurological tests this week -- he may not start. Tomlin said veteran cornerback Ike Taylor also could be benched, with the Steelers wanting to take a long look at Burnett and fellow rookie Keenan Lewis.

Asked how a veteran-laden team would react to changes made to the starting lineup, Tomlin said, "I think they understand it, and I think to a degree, they will agree with me. That's the nature of this thing. We can't stay status quo in terms of how we approach everything and expect that pattern of behavior and outcomes to change.

"That's unrealistic. That's hopeful. I'm not a hope mentality person. I think our guys are of the same mindset, so I don't expect any surprise or discontent in regards to this approach."

Tomlin could be limited in the number of changes he makes because of the 53-man rosters in the NFL.

If he feels compelled to shake things up, that is because the Steelers' fourth-quarter struggles, particularly on defense, could keep them from getting a chance to defend their Super Bowl title.

The Steelers are yielding 105.1 yards per game in the fourth quarter, and 43 percent of the points they have allowed this season have come in the fourth quarter.

Everyone seems to be at a loss to explain why a vaunted defense has been so vulnerable in the fourth quarter. And, as defensive end Brett Keisel said when asked if he could pinpoint the reason for the late struggles, "I wish I could, or I would have addressed it after the first game."

Half of the turnovers the Steelers have forced have come in the fourth quarter, but they only have 16 takeaways. Of their eight interceptions, none have been made by a cornerback.

"Obviously, we're a very average Football team as we sit here today. And our recent record indicates that that might be a kind assessment of it," Tomlin said. "I'm just being very realistic of where we are. I think we all need to do that because that's going to give us the necessary clarity to change it."

Tomlin's takes

On whether the extended absence of strong safety Troy Polamalu can be attributed to the defense's struggles:

"I think we're capable of playing winning Football with or without Troy. Are we different? Yes, because Troy's a unique individual. He brings a unique skill set. Maybe the ceiling's different, but the floor, the standard of expectation, is the same that we're capable of playing winning Football without him. I don't worry about that. I tend to focus my energies on the guys that do play and their level of preparation and their level of play as opposed to guys who aren't available."

On the psyche of the Steelers after they have lost four consecutive games:

"You've got to acknowledge the potential that this is a shaken group, which has swallowed a lot here of late. We're going to have to become one with ourselves, if you will, individually and collectively."

On the week that lies ahead:

"It's going to provide information to me as far as who is legitimately mentally tough and who can stand the test of some adversity because we have some, who's going to lead the charge in terms of getting us out of this and winning a Football game. I'm going to be very interested to see who those people are."

On whether he is satisfied with the leadership he has gotten:

"We've got quality leaders, we've got quality guys. It's not about the type of people that we have or the type of Football character we display. It's about making plays, it's about the performance. Who we are and what we do are two different things. I'm going to call on that leadership and really look for others outside of those known leaders to provide quality leadership."