Ed Zurga/Associated Press

There's no question that Ben Roethlisberger is one of the greatest quarterbacks of his era, and he'll most likely find himself enshrined in the Pro Football Hall of Fame on the first ballot. He's been on two Super Bowl-winning teams, and he ranks in the top six from his rookie season of 2004 to now in starts, completions, passing yards, passing touchdowns and yards per attempt.

If you're into the Quarterback Wins stat (which I generally am not), you could add that only Tom Brady and Peyton Manning have more "wins" than he does in that time.

That said, Roethlisberger's boom-or-bust style does have its drawbacks. He has been prone to streaks of iffy play throughout his career, just as he has had stretches in which he looks nearly invincible. Unfortunately for the Pittsburgh Steelers, he's been going through one of those rough patches over the last month of the regular season and into the playoffs.

From Week 13 through the divisional round, the Steelers have not lost a game—in fact, they haven't lost since they fell 35-30 to the Dallas Cowboys in Week 10—but it'd be tough to say the streak has much to do with their quarterback.

Right now, running back Le'Veon Bell is torching the entire league, receiver Antonio Brown is at his best, the Pittsburgh offensive line has quietly become one of the NFL's most imposing under line coach Mike Munchak and the defense has taken strides forward since linebacker Ryan Shazier returned from injury. There's enough there to win without your quarterback's playing well, and that's good, because Big Ben hasn't been of late.

In December, Roethlisberger completed 86 of 136 passes for 1,074 yards, six touchdowns and six interceptions. Things haven't been any better in the postseason—through the wild-card and divisional wins over Miami and Kansas City, respectively, he completed 33 of 49 passes for 421 yards, two touchdowns and three interceptions.

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More distressingly, the things that usually work about his game have been off.

Roethlisberger was one of the NFL's best deep passers in the regular season, leading the league with 13 touchdowns on passes of 20 yards or more in the air with just three picks. In the postseason, however, he's completed just one such pass on four attempts. To put that in perspective, Green Bay Packers quarterback Aaron Rodgers has nine deep completions on 23 attempts. And New England Patriots signal-caller Tom Brady, who Roethlisberger will see in the AFC Championship Game, completed six of 11 deep passes in one playoff game.

Roethlisberger has also been unusually balky under pressure (one completion and one interception in four attempts under pressure in the playoffs), and the Steelers have abandoned the play-action passing game in the postseason—Roethlisberger has completed two of three play-action attempts for just 22 yards. In an offense where play action off a dominant run game should be an open invitation for deep-shot plays, that's alarming.

I asked Cian Fahey, our NFL1000 quarterbacks scout, for his take on Roethlisberger's recent regression.

"Ben Roethlisberger has quickly become one of the least predictable quarterbacks in the NFL. He is still capable of consistent brilliance and is one of the most intimidating quarterbacks in the league, but his decision-making week-to-week has been puzzling," Fahey said.

"Look at the Miami Dolphins game two weeks ago—his interception in the fourth quarter was inexplicable considering the situation, but also considering how long he held the ball to allow [Dolphins defensive end] Cameron Wake to hit him. Against Kansas City he was managed well because the offense primarily relied on Le'Veon Bell, but his inability to throw with precision once the field tightened was a big reason for their inability to score a touchdown.

"It's hard to see the Steelers upsetting the Patriots if Roethlisberger doesn't look more like the superstar everyone knows he can be," Fahey added.

Let's start with Roethlisberger's interception against the Chiefs and the adjunct fact that the Steelers had to kick six field goals to beat the Chiefs—and if a controversial hold against Kansas City left tackle Eric Fisher wasn't called on their late two-point conversion attempt, it would have been an 18-18 tie. These types of red-zone blues will not play well against the Patriots.

The Chiefs' interception came with 6:12 left in the second quarter, and it's one example of something we're seeing a lot from Roethlisberger through this slump: bad reads.

He has Brown (84) running an outside release on cornerback Terrance Mitchell (39), but he fails to account for the fact that safety Eric Berry (29) has walked right into his line of sight and linebacker Frank Zombo (51) has dropped back from a pass-rush look. Zombo deflects the pass right to Berry for the pick. The only way this throw would have worked is if Roethlisberger threw it up as a fade and Brown beat Mitchell to the ball. This read and throw? Far too risky, and it shouldn't be surprising that it went this way.

Roethlisberger threw two interceptions in Pittsburgh's wild-card win over the Dolphins, and they showed different issues. The first came with 1:08 left in the first half, and he set to throw to Brown just before the wideout broke his route into Miami's zone. But Roethlisberger had to run out of pressure before he could make that throw, and the scramble upset the timing of the play. At that point, he threw off balance and a bit high—certainly a ball Brown could have caught, but it appeared to be a shock to him. Safety Michael Thomas had an easy pick off the bounce.

The second pick came with 4:34 left in the game, and this was the situational issue Fahey was talking about. The Steelers are up 30-12, and here's Roethlisberger, making a terrible decision to throw as Cameron Wake (91) already has him in his grasp and halfway down.

Big Ben has made these types of throws before—perhaps no quarterback in NFL history is better at throwing dimes with defenders all over him—but why here? When he throws it a good two feet over the head of tight end Jesse James (81), this looks more like a play we'd see out of Blake Bortles. Cornerback Xavien Howard (25) got quite a gift here.

Roethlisberger's problems with timing are a big part of this slump. Here, early in the third quarter against the Baltimore Ravens in Week 16, he has tight end David Johnson (82) on a simple option in-cut. Johnson is supposed to hit the spot where Roethlisberger is throwing, and when linebacker Zach Orr (54) drops into deeper coverage, Johnson should have the outside of the crossing route open. But the throw comes before Johnson can get to the spot, and Orr makes an athletic play to pick it off.

Could it be argued that linebacker C.J. Mosley (57) got away with a small tug to upset the timing of the route? Perhaps, but there isn't enough there to excuse the off-key nature of the play.

Roethlisberger's worst game of this slump came against the Buffalo Bills in Week 14, when he threw three picks. When studying multi-interception games, it's always instructive to go through and mark which ones aren't entirely the quarterback's fault—usually, there's at least one in which the receiver, the play design or the protection is to blame to some degree. But against the Bills, it was a litany of plays in which Buffalo defenders exploited the poor timing of Roethlisberger's throws to his targets, and they were jumping routes all over the place. It was elementary.

This pick, with 8:45 left in the first half, was especially egregious. Here, he has Brown to the left in a closed formation, with cornerback Stephon Gilmore (24) on Brown. This was either miscommunication on the design of the route between quarterback and receiver or simply a horrible throw by Roethlisberger. Brown shakes free of Gilmore's tight coverage and has an opening underneath. But the throw is more to Gilmore than to Brown.

Can Roethlisberger turn it around in time to get the Steelers past the Patriots and to another Super Bowl? It's possible. But one thing's for sure: Against this Patriots defense and with the distinct possibility of a shootout, Pittsburgh will need Big Ben's best. It's just hard to know what that means right now.