You didn't have to be an NFL defensive coordinator to figure out that the Eagles had trouble stopping a good running game at times last season. Occasionally, they had trouble stopping an average running game.

You didn't have to be a defensive coordinator to notice this, but Jim Johnson, who holds that job for the Eagles, came to the same conclusion you did.

"We're seeing a lot of good running games, no question about it," Johnson said. "Maybe it's us."

Maybe so. The Eagles were 26th in the NFL in rushing yards per game allowed, 24th in average yards per rush (4.5) and dead in the middle of the pack in opponents' percentage of success on third down.

When it came time to put their shoulders low to the ground, stop the ballcarrier and drive him backward, the Eagles' defensive players couldn't tell time. For reference, see the final game of the season, the playoff loss to New Orleans. Not only did Deuce McAllister romp around for 143 yards, but when the Eagles punted away the ball in the final minutes, the defense couldn't keep McAllister from getting the first down that effectively ended the game.

"I felt at times we were small at tackle and linebacker, especially," Johnson said. "We were small at linebacker and wanted to get bigger at the [strong side]. That's why we drafted Chris Gocong last year and Stewart Bradley this year. Then, of course, Takeo Spikes came free. He's a nice size linebacker who can play [all three positions]. All of a sudden, we're bigger at linebacker. We got a couple of tackles we drafted and free-agent signings. We're bigger at tackle now. It's going to help us."

For a team that has the reputation of paying no attention to its linebackers, the Eagles are suddenly paying attention. Giving up all those yards has something to do with that, of course, but adjusting to the way the game is changing in the NFL is a factor as well.

The ability to play pass coverage combined with the ability to stop a running play is a difficult balance. Speed helps more on the former, size more on the later. The entire job description of a linebacker requires a split personality, which is reflected in the name of the position itself. You have to play the line and be in back of it at the same time.

Obviously, the Eagles have had some trouble sorting this out. Last season, with either an aging or a slumping Jeremiah Trotter in the middle, bracketed by the ponderous Dhani Jones and smallish Matt McCoy, the deficiencies were apparent.

Spikes is three inches taller and 15 pounds heavier than McCoy at the weak-side position. Gocong is an inch taller, 20 pounds heavier than Jones at the strong-side position, and Stewart Bradley is just as big. If Omar Gaither takes more plays from Trotter, he makes up in mobility what he lacks in sheer heft.

If the plan is to throw some bulk against the run, the Eagles are headed in that direction. Of course, the bulk has to play well, and that's not something that can be determined in a May minicamp. Everyone looks good, or good enough, in skeleton drills and glorified walk-throughs. And the bigger the better.

"Size is not everything at that position," coach Andy Reid cautioned, asked about the linebacker spot. "You have to be able to move. That's the important part. If you are going to be bigger, you still have to have quick feet and speed."

On the defensive line, among players the Eagles hope can contribute, tackles Ian Scott and Montae Reagor will take up some room, as will 2006 first-round pick Brodrick Bunkley, if he can get on the field. Draft pick defensive end Victor Abiamiri, listed at 6-foot-4, 267 pounds, is nearly the largest man at that position on the roster.

"We think he can be up to 275 or 280 pounds," Johnson said. "He's 6-4 and can rush the passer and stop the run. Now, we don't have pads on, but he does look good."

So the transition continues as the Eagles work toward having a defensive team that isn't knocked off the ball, can stop the run and - for that matter - can play as well as the offensive side of the roster.

Maybe that is where the majority of attention always goes (see McNABB, Draft, Reaction to:), but the offense wasn't necessarily the team's biggest problem last season. Under Donovan McNabb before his injury, and under Jeff Garcia, the offense was productive enough. It was the defense that couldn't close the door.

The Eagles noticed, and the physical makeup of the front seven is being revamped. Will it be better? That's the question. It will be different, though, because it didn't take a defensive coordinator to see the problem. All it took was a ticket.

Contact columnist Bob Ford

at 215-854-5842 or bford@phillynews.com.

Read his recent work at http://go.philly.com/bobford.