How John Greco Starting at Center Will Affect Browns' Stellar Offensive Line

Ever since Alex Mack was drafted 21st overall back in 2009, he had brought stability to the center for the Cleveland Browns.

In fact, since Mack's arrival, the Browns offense had not played without him before his season-ending leg injury occurred in the second quarter of last week's win over the Pittsburgh Steelers. 

Veteran lineman and starting right guard John Greco stepped in and performed well in Mack's stead as the Browns continued to roll the Steelers for the remainder of the contest.

However, the Browns are now forced to face the reality that Mack is done for the season, and Greco is the starting center for the remainder of 2014.

While the center position is a widely overlooked one, it is an incredibly important part of an NFL offense. The center typically makes pre-snap reads, communicates protection changes with the rest of the offensive line and then exchanges the football with the quarterback to start the play. He also has to effectively block downfield on running plays and protect the quarterback when he drops back to pass.

Should the center fail to properly handle any one of these responsibilities, the end result can be disastrous.

Mack, a two-time Pro Bowler, is widely considered one of the best veteran centers in the game today, and his loss simply cannot be overstated. He was rated third overall among centers by Pro Football Focus (subscription required) before the injury and helped lead the charge for a Browns offense that Pro Football Focus currently rates tops in the NFL.

The Browns offensive line continued to play at a high level against the Steelers with Greco in at center and reserve lineman Paul McQuistan taking over Greco's spot at right guard. However, they will be making their first starts at their new positions on Sunday on the road against the Jacksonville Jaguars.

A notable drop-off should be expected.

"It's a huge blow," offensive coordinator Kyle Shanahan said Thursday, via ESPN.com's Pat McManamon. "It's just part of the business, but Alex is as good a football player as I've been around. We're going to miss him a lot, and you don't replace a guy like that. He's too special of a player."

While Greco has performed extremely well this season (he is currently rated as the league's seventh-best guard by Pro Football Focus), Sunday will mark the first time in his pro career that he will start a game at center.

Greco doesn't have the same experience working with quarterback Brian Hoyer that Mack had enjoyed, and he doesn't possess the same elite level of athleticism as the former Cal standout either.

Mack's athleticism played a huge role in offensive coordinator Kyle Shanahan's zone-blocking scheme. His ability to get upfield, pull and effectively engage defenders was a big part of Cleveland's third-ranked rushing attack (146.4 yards per game on the ground). 

Runners are expected to make one cut and hit the hole hard in the zone-blocking scheme, and if things are muddled at the line, it can create problems. Expect Shanahan to keep things a little more simple on the ground as Greco grows into his new role.

The good news is that Greco is in his fourth season with the Browns and has a built-in rapport with the other members of the line, including McQuistan, rookie guard Joel Bitonio, right tackle Mitchell Schwartz and perennial Pro Bowl left tackle Joe Thomas.

This sense of continuity puts the Browns in a better position than if the team had signed a journeyman center off the street. 

	Career Starts	2014 Starts	2014 Position Rank
Joe Thomas	117	5	3rd
Joel Bitonio	5	5	3rd
Alex Mack	85	5	3rd
John Greco	33	5	7th
Mitchell Schwartz	37	5	10th
Paul McQuistan	52	0	?

Greco is also a capable pass-protector. He is ranked fourth overall among guards in pass-blocking efficiency by Pro Football Focus. He was tested early and often by the Steelers' interior pass rush last week and held up admirably. 

If the Browns passing game suffers from Greco's presence, it will likely be due to issues with the quarterback-center exchange or with pre-snap adjustments. I would expect the Jaguars and other future opponents to test Greco's capabilities with interior blitzes and stunts.

Cleveland will likely counter by assigning some of the protection responsibilities to Thomas, another player who has never missed a snap for the Browns.

In Greco's old guard spot will be McQuistan, a tenth-year player who started 14 games for the Super Bowl champion Seattle Seahawks a season ago.

McQuistan is likely to be the real weak link along the Browns line moving forward, as he has primarily played as an offensive tackle and ranked just 71st in the NFL at that position in 2013, according to Pro Football Focus.

The good news for McQuistan is that he is an experienced veteran and will be surrounded by some of the top offensive linemen in the game today.

Shanahan continued to call running plays to the right side following the line shift a week ago, and the team still had success. However, opponents now know that this is where the line is likely vulnerable and will likely attack the right moving forward.

Cleveland can counter with multiple-tight end sets and a steady dose of rookie fullback Ray Agnew, who Pro Football Focus ranks as the league's 16th-best blocking fullback. 

The reality is that the Browns offensive line is a better, more athletic unit with Mack at center and Greco at guard. Barring another injury, however, the group is well-suited to handle the coming changes and still function as a top-tier unit.

Expect some more simplified play-calling as the offense adjusts to its new lineup and perhaps a little lower efficiency while running the football. (The team is currently averaging 4.4 yards per run play.) However, don't expect the Browns offense to suddenly stop playing like one of the best units in the game, even with one of its best players now a spectator.