The offense simply can't be successful with the poor production it's received from the game's most important position.
There were different reasons for those struggles: poor execution and predictability.
Make no mistake, as the trigger man, Manuel is at fault for his own shortcomings. Better play-calling won't help him hit open receivers. Better play design won't make him stop staring down his first read before checking down to a running back. Those are areas Manuel has to improve on his own.
That doesn't mean better play-calling and design aren't in order, though. But for it to have any effect, Manuel's game must improve in certain areas.
One of those areas is his ability to throw the ball into tight windows in coverage.
On this play, the Bills came out with the 12 personnel grouping—one running back, two tight ends, two wide receivers—on 2nd-and-11 in the first quarter. Wide receiver Stevie Johnson (circled in yellow) was in the slot, with linebacker LaMarr Woodley matched up on him.
That is a matchup that's considered a win for the offense, and Manuel made the right decision in making the throw.
Johnson came open on the curl, but Manuel delivered the throw to Johnson's back shoulder, right where Woodley could make a play on the ball. Fortunately for Manuel and the Bills, Johnson was able to get in the way of the pass before it could be intercepted.
With a better throw into the open space, though, Johnson might have picked up a first down. Instead, the Bills went three-and-out and punted on a drive that began at the Steelers' 44-yard line.
This was a recurring problem throughout the day, as bad throws accounted for nine of his 17 incomplete passes. But I thought CBS analyst and former NFL quarterback Rich Gannon offered an interesting nugget during the game's broadcast.
"In talking to some Pittsburgh Steelers defenders, they said that he's a guy that wants to see them open instead of throwing them open," said Gannon.
Manuel needs to become a quarterback who can throw his receivers open, a passer who doesn't need his targets to be wide open or settled in a convenient crack in zone coverage.
There has been some consternation over the number of checkdowns thrown by Manuel as well as the lack of deep passes called by the Bills' coaching staff. According to Pro Football Focus (subscription required), Manuel throws a pass 20 yards beyond the line of scrimmage or further on 12.7 percent of his attempts (tied with Aaron Rodgers and Eli Manning for 17th out of 36 qualifying quarterbacks). Manuel's accuracy on those throws, however, has been an abysmal 25 percent (34th on the same list).
Manuel's poor accuracy on deep throws was on display again in Week 10, as he completed just two of seven that traveled 10 yards or more beyond the line of scrimmage.
"They did a lot of coverages that were deep and had deep safeties and things like that," Manuel said, via ESPN's Mike Rodak. "So at times it was tough to stretch the ball down the field. You can only take what they give you. There's no point trying to force balls down the field if it's not there."
On the one occasion he did force a throw into deep coverage, it was, not surprisingly, intercepted.
Steelers safety Ryan Clark was able to get a break on the ball from his spot in Cover 2, reading the route of wide receiver Marquise Goodwin and getting there in time to pick it off cleanly.
Manuel avoided turnovers all day as a result of his willingness to take checkdowns, but any offense will struggle when a defense can take away the long play without fear of a quarterback taking advantage of the available space underneath.
There is a problem with continued checkdowns, but not just the presence of them; there's a timing issue as well.
On 3rd-and-6, the Bills came out with the 11 personnel grouping—one running back, one tight end, three wide receivers—and the Steelers matched up with their nickel defense.
To their credit, the Steelers were in a very sound defense for this situation. As Manuel stated after the game, Pittsburgh was in a deep coverage, taking away all the vertical throws. The problem, however, is that both tight end Scott Chandler and running back Fred Jackson were running routes in front of the first-down marker.
That made it too easy for the Steelers defense to crash downhill and take away the opportunity for yards after the catch when Manuel pulled the trigger on the short throw to Jackson.
Manuel had nine checkdowns on the day out of his 22 completions. As a result, he averaged 3.97 yards per pass attempt against the Steelers. That simply won't cut it if Manuel wants to be a winning quarterback. He averages 6.03 on the season, indicative that this is a more wide-spread problem than just Sunday.
It all goes hand in hand. If the Bills want those long passes to be available, Manuel has to do more to make defenses pay.
It's Manuel's responsibility to keep his eyes downfield and keep looking for open receivers to pick up bigger plays, but the coaches need to reinforce this idea in practice.
There are other things the coaches can do to help Manuel's cause.
As the game against Pittsburgh trudged on through the final minutes, with the Bills mounting a meaningless last-minute drive to save face on the scoreboard and the stat sheet, Gannon dropped knowledge on Manuel's struggles on the day and some of the reasons for those struggles.
"I'd like to see EJ Manuel...under center more," Gannon said. "I think you develop bad habits if you're constantly in the gun. I've seen him miss some throws [where] I think he's got some issues with his footwork, his accuracy...He's missed a lot of receivers either low or behind."
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This is especially appalling when you consider the incredible balance the Bills have had between running and throwing the ball. Through Week 10, the offense posted 312 pass attempts against 304 rush attempts.
"I don't think it has anything do with the knee," Gannon added. "I'd just like to see him under center more. I think it helps with the footwork, it helps with the play-action game, it's easier to run the football under center. It gives you more options, as opposed to in the gun."
As a result of Buffalo's imbalance against the Steelers between runs (22) and passes (39), one might surmise that Bills were not afraid to put the ball in Manuel's hands in his first game back. However, the Bills spent the final 32 minutes of the game trailing by at least seven points.
They became too predictable in the first half, calling seven runs and three passes on their 10 first downs. The Steelers defense began coming up on first down, and it took until the second half for the Bills to do anything about it.
With their backs against the wall, starting a drive from their own 8-yard line, the Bills called a play-action pass to draw the defense up.
Johnson ran a 10-yard post, breaking over the middle, where there was a gaping window for Manuel to complete the pass. There were three defensive backs in deep coverage, keeping the play in front of them, but the front was expecting run.
That gave Johnson all the room he needed to make the catch and keep on running.
Thus, even with the shortcomings of the offense and the play-callers, there's some positives to come out of this.
That's not all too surprising, considering the offense was at least serviceable with backups in the lineup from Weeks 6 through 10. The layoff may have hurt Manuel.
"The kid missed four weeks and just came back. He's trying his best," head coach Doug Marrone said, via Rodak. "If you want to know exactly what happened out there, he's going through his footwork too quickly and [he's] not as slowed down to see things develop as quickly."
That was evident on his attempted fade route to Johnson, when he simply pulled the trigger too soon and didn't even give his receiver a chance to make a play.
Not only had Johnson not even gotten off the line of scrimmage, but the ball was delivered well out of bounds and would likely have been over Johnson's head even if Manuel's timing was better.
Perhaps to avoid making excuses for his play, Manuel declined to blame the rust.
"I didn't feel rusty. I felt good," Manuel said. "I don't think that is a big deal with missing games or anything like that. You have to feel. You can tell when you have pressure. You can tell when guys are getting closer to you, so I don't think missing games has anything to do with the internal clock."
More time on the field could help, but for now, the Bills need to focus on finding ways to create separation for their receivers underneath, giving Manuel easy reads on throws besides checkdowns. Manuel must also get back to work on his accuracy.
All parties involved have work to do if the production in the passing game is going to improve, but the Bills have a general outline of what they need to do.
Now, it's up to the coaches and Manuel to put in the work to make it happen.
Erik Frenz is also a Patriots/AFC East writer for Boston.com. Unless otherwise noted, all quotes were obtained firsthand or via team news releases.