CHARLOTTE - One of the mysteries about the Carolina Panthers' 1-3 start involves the play of what was supposed to be one of the NFL's best offensive lines.
All five starters returned this season, led by left tackle Jordan Gross, but so far the line has struggled both in run blocking and pass protection.
The Panthers rank 23rd in the NFL in rushing and have yet to get a 100-yard performance out of either of their highly-regarded backs, DeAngelo Williams or Jonathan Stewart.
According to stats.com, the offensive line has given up 10 sacks through four games. That is half of the Panthers' team total for last season.
"We're a little slow right now, but it'll come," said right guard Keydrick Vincent. "We've just got to keep working on it."
But what has happened since last season, when the Panthers ranked third in the NFL in rushing and eighth in fewest sacks allowed?
"This is a new year," said left guard Travelle Wharton. "People attack you different."
The Philadelphia Eagles surprised the Panthers with an exotic mix of blitzes in a 38-10 season-opening loss at Carolina. Opponents since then have used eight-man fronts to thwart the running game and have double-covered Steve Smith to slow the Panthers' receiving star - all tactics Carolina saw last season en route to a 12-4 record.
Coach John Fox is protective of the offensive line, saying he was not sure the unit's play should be singled out.
"We've had the same guys in there," he said. "It's probably (that) we need to improve.
"We do that in practice and hopefully we'll continue to get better."
Unlike on defense, injuries have not been an issue hindering the offensive line's development. Its five starters have been healthy since the start of training camp.
There is plenty of talent on board. Gross and right tackle Jeff Otah were first-round picks, while center Ryan Kalil was a second-rounder. Wharton is frequently spoken of as having Pro Bowl potential at left guard.
Gross acknowledged he expected the line to pick up where it left off last season, especially since each of the five starters participated in the offseason conditioning program together.
"We've definitely been working hard," he said. "We've got a lot of reps together. It just hasn't seemed to click yet - running the ball, protection, everything."
Gross was particularly upset with his play during last week's 20-17 victory against Washington, when he appeared to give up two sacks and apologized to his teammates.
"You take it personally," said Gross. "I want to be somebody the team can count on. If I do bad, I'll say (so). Each year, I expect more out of myself. I can do better than that."
Quarterback Jake Delhomme said he and other teammates respect Gross' accountability.
"That's what's so good about him," said Delhomme. "He didn't say, 'Oh well, it was just one of those days.' It bothered him. It affected him. It means something to him. To me, that's what it's about."
Several players mentioned Wednesday that the Panthers' running game got off to a slow start last season, too.
After four games in '08, Carolina ranked 19th in the league in rushing and, like this year, had not had a back to run for 100 yards in a game. But that all changed when the Panthers beat Kansas City in their fifth game, beginning a seven-game stretch in which Williams rushed for 100 yards five times and Stewart once.
"I know we finished better than we started last year," said Gross.
Gross is looking for similar improvement as this season progresses. Already, he said, the communication problems the offensive line experienced against Philadelphia have gotten much better.
"I think we'll turn it around," he said. "It's early still. Hopefully, in another four games from now, we're not talking about this."