Ben Roethlisberger rides a cart into the locker room, his face contorted in pain. Tony Romo supports his crumpled shoulder with a sling. Drew Brees misses his second start in 11 years. Matthew Stafford's ribs and arms are battered. Andrew Luck is taking practice days off to nurse his ravaged body.

NFL quarterbacks took a beating in the first three weeks of the season, so much so that a long-simmering issue has been elevated into mainstream discussion. Offensive line play has deteriorated in a way that's apparent to both to the expert and novice eye, endangering the league's quarterback star system and threatening the aesthetic appeal of the game.

The situation has descended into an "epidemic," Hall of Fame executive Bill Polian said recently on ESPN, and there are no easy solutions.

"It's a sad state of affairs," Polian said. "And if it keeps up, we're going to be talking about backup quarterbacks playing a lot. Because when you've got problems with the offensive line, you get the quarterback on his back."

The NFL has already seen 38 different starting quarterbacks through the first 48 games of 2015, its second-highest total in the past 15 seasons, per the Elias Sports Bureau. Failures in pass protection are not the only cause -- Jay Cutler, for example, pulled his hamstring while chasing an interception return -- but those who follow the sport closely are convinced the injuries reflect a collapse of reliable blocking skills across the board.

"I've been harping on that for two years," said Matt Williamson, who scouts the NFL for ESPN. "I don't think the average fan realizes what an O-line shortage there is now. There are very few teams with lines that have had continuity, and there's certainly less Hall of Fame-level guys playing right now. You don't look around and see many of the Jonathan Ogden, Orlando Pace and Walter Jones types anymore."

Let's take a closer look at where line play is in the league, how it got there and what -- if anything -- can be done.

The facts

The performance of offensive linemen is as difficult to quantify as anything in football, and the most popular statistic -- sacks allowed -- is arbitrary. But a review of uniform advanced metrics reveals a notable decline in recent years.

Between 2009 and 2012, NFL quarterbacks were pressured -- defined by ESPN Stats & Information as sacked, hit or put under duress -- on 22.3 percent of their dropbacks.

That figure has risen to 25.6 since the start of 2013, an increase that works out to about 1.25 additional pressures per game, based on 600 dropbacks a year.

Along with allowing added pressure, offensive lines so far this season are providing less running room and taking more penalties than they did in the same stretch of time last season.

Average rushing yards before contact has dropped eight percent, from 2.35 yards per rush during the first three weeks of 2014 to 2.19 yards now. Accepted penalties for either holding or false starts, meanwhile, have risen 20 percent from a total of 219 during the first three weeks of last season to 275.

Those numbers are no surprise to offensive line coaches and longtime observers of the position who noted the trend long before this season's run of quarterback injuries.

"There's definitely something to it," said retired guard Steve Hutchinson, whom many regard as a future Hall of Fame inductee. "No one in the game can stick their head in the sand and say it's not happening."

The cause

Hutchinson, who is now a college football analyst for Fox Sports, traces the issue to the rise of the spread offense at the high school and college level. In most cases, the scheme asks offensive linemen to operate out of a two-point stance, fundamentally changing their approach and limiting their technique.

"You watch football at most levels now," Hutchinson said, "and in the running game, nobody knows how to attack and snap their hips. Everything is stand up, turn sideways and run. That's the zone scheme. It's push and pester, just kind of get in somebody's way, and let the running back find the crease. There's no more moving the line of scrimmage, no more establishing the line, no more wearing defenses out by the fourth quarter."

In pass protection, Hutchinson surmises, spread linemen "are just told to get in front of a guy and don't get beat clean." Some level of pressure is expected, he said, leaving it to quarterbacks to release the ball or extend the play before a sack occurs.

That approach already appears to have hit the NFL level. From 2009 to 2012, quarterbacks under pressure took an average of 3.45 seconds to release the ball. Since 2013, that number has dropped to 3.35 seconds.

"If that's what they're going to do," said retired lineman LeCharles Bentley, "then they're just going to keep getting quarterbacks hurt. It is what it is. If you keep asking a quarterback to do non-quarterback things, they get hurt."

When these spread lineman arrive in the NFL, teams have a more limited amount of time to teach them pro-level technique. Indeed, Polian has targeted the NFL's collective bargaining agreement (CBA) as the root problem.

Enacted in 2011, the CBA significantly limits offseason practice time and has cut back on training camp time as well. The general split of the numbers we've discussed help support Polian's point, and those in the game can rattle off the drills, teaching and development that no longer occurs.

Former NFL center Hank Fraley, who is now an assistant offensive line coach for the Minnesota Vikings, recalled a time when linemen reported to team facilities in March to begin working on technique.

"You had time to work with the bags, to practice sliding and that kind of thing," Fraley said. "You weren't necessarily being physical about it, but just working that technique and timing. You definitely lose some of that now. There just isn't the opportunity to do that. You don't have things like bag punching going on. They don't report until April, and when they do, you're very limited with what you can do with them, and that throws off development for sure. Now, guys might have to find places to do that on their own."

Bentley operates one such facility. O-line Performance, based in Chandler, Arizona, has filled in the offseason technique gap for some players. But Bentley said that extra work alone is not a full solution.

"Anything that's a learned skill requires volume," he said. "But the problem with football in general is you can't work in volume. You can't take a guy out there and bang his head over and over again because the body breaks down."

Hutchinson said he understands Polian's point about the CBA and knows "you can't get as good at something with less reps." But, he said, "you can't blame the weakness of a whole area on just one thing."

He added: "Fifty percent of a football practice at training camp is a waste of time. You can double the reps on things you really need to work on and take out the other stuff. But I just think teams are looking at the situation with guys coming up from college and figure there is no use paddling upstream.

"If you're getting guys that, since the day they started playing in pee wee, never got in a three-point stance and never really did any drive blocking, if all they have done is just run sideways and pushed people, then you're not going to get it turned around at the pro level."

The fix

What can be done? Polian has championed the idea of a developmental league that would provide opportunities for in-game training. The NFL, however, just completed its eighth offseason since shuttering NFL Europe and there are no known plans to replace it.

The CBA, of course, doesn't expire until after the 2020 season. It seems unlikely that players will want to give back their offseason as part of the next agreement. So any solutions likely have to be developed within the confines of the current CBA structure.

To avoid "paddling upstream," Hutchinson envisions a day when the NFL draws its linemen from the handful of schools that run pro-style offenses or whose coaches are known to be teaching NFL-necessary technique. Bentley, meanwhile, thinks the NFL must overhaul the way it scouts for offensive linemen and the metrics it uses to evaluate them.

In Bentley's view, none of the drills at the NFL's annual scouting combine will help reveal offensive linemen who can succeed at the pro level.

"What's happened at offensive line positions is players have evolved from physical guys to guys that physically look impressive. They're running faster and lifting more weights because that's what they'll have to do at the combine. But the fact is, much of what we're measuring isn't going to translate into high-level performance.

"There are a lot of players out there who can play and should play in the NFL," he added. "The problem is what they want, and what they deem to be an offensive lineman in 2015, they don't fit that box. They're just not 6-foot-7 and running the 40 in 4.6 seconds."

Bentley has developed his own set of metrics, which he said are proprietary to O-line Performance. But it's safe to say that they involve identifying less physically appealing prospects who have demonstrated the strength and power to defeat defenders rather than just get in their way.

Otherwise, there seems no way out of the box. The NFL is at 38 starting quarterbacks already -- with 208 games left to play.

Jacob Nitzberg of ESPN Stats & Information contributed to this report.