"But you've got to be able to run from sideline to sideline. You've got to play multiple positions."
Logan can fulfill the traditional run-stopping duties of a nose tackle, however, or the Eagles wouldn't have traded Isaac Sopoaga in the middle of last season and handed the starting job to the rookie.
That didn't stop the Eagles from drafting Allen in May. But they didn't select the Wisconsin product because they lacked a space-eating nose tackle, as some suggested. They wouldn't have waited until the seventh round if that were the case.
The Eagles took Allen because he was, in their eyes, a versatile 330-pounder. He had the obvious two-gap capabilities. But he also had quick feet and pass-rushing skills that have been evident since the Eagles starting wearing pads and hitting in training camp.
"The ability to do both, I think, is what attracted us to him," Eagles coach Chip Kelly said. "But he does for a 335-pound guy have some suddenness to him and he's got a knack and feel of how to win the hand battle up front.
"It's just impressing when you have a nose that has a little bit of a pass rush to him. I think it's a bonus."
Logan has missed most of camp with a hamstring injury, but he said Monday, before the Eagles were to travel to New England for scrimmages against the Patriots, that he was 100 percent. In his absence, though, Allen has capitalized on additional opportunities.
Damion Square started at nose tackle in the preseason opener at Chicago, but Allen made an impression against the Bears' second unit. He bull rushed the center into the quarterback, nearly causing a fumble, hustled downfield to stop a screen, and lumbered to the sideline to tackle a running back.
The sample is small, but Allen's play has the coaches giving him an inordinate amount of praise for a seventh-rounder. Logan will likely open the season as the starter, but defensive coordinator Bill Davis will have the good problem of figuring out what to do with Allen.
"You play them both," Davis said. "We rotate anyway. We are constantly rolling."
Logan isn't assured of anything, but there is potential upside. He was new to a two-gap, 3-4 scheme and improved last season once he was given the starting job. The majority of his snaps came at nose tackle on base downs, but he also pass-rushed as an end or a tackle when the Eagles went with four down lineman.
Logan recorded two sacks and seven hurries in 279 pass-rush opportunities.
"I feel like I can rush the passer. Coach feels like I can," Logan said. "It just depends on the situation in the game. But I do feel like I will be on the field more that I was last year."
But what about against the run? The Eagles ranked 10th in the league in rushing defense, fourth in rushing yards per play (3.8). But they gave up 185 yards on 36 carries to New Orleans in the playoffs. Davis was intent on stopping Drew Brees, but Logan said the line was late in adjusting to the Saints' run tendencies.
"It wasn't like they were just blowing us off the line," he said.
Logan added five pounds in the offseason. He injured his hamstring near the start of camp. But he's been an active teammate, often seen giving Allen and some of the other young linemen tips.
When Allen ran off Soldier Field during one personnel switch, Logan was first to greet him. Logan is known for his unselfish ways. He was awarded the No. 18 uniform at LSU, given to the player who best exemplifies selflessness.
"He's a great learner," Logan said of Allen. "He takes advice, he learns from it and he goes out there and executes it. . . . He's really aggressive. That's me, that's my style of play, and that's what I like about him."
It takes one nose tackle to know one.