Zone blocking-schemes are a fickle beast in the NFL, and their resounding success stories are balanced by the failures. The most notable and often cited example of the former is the Houston Texans, a team which has used the scheme that’s perfectly suited for Arian Foster’s skillset to clear room for their lead running back to run for 4,264 yards over the past three seasons, with 41 touchdowns. His highest single-season total during that stretch was 1,616 yards. Yeah, pretty good.

Then there’s the tale of woe that is the Raiders. Sure, much of Darren McFadden’s failures under their zone-blocking scheme installed prior to the 2012 season was a result of his inability to not break things (he missed four games). But when he was healthy, McFadden was mostly horrible. He averaged 3.3 yards per carry and 58.9 per game, while scoring only twice on the ground.

This offseason the Raiders announced a move away from zone blocking, and McFadden was rather excited:

“This is very exciting for me. I am the type of guy who likes to go downhill, make a cut and go; that’s my thing. We’ll mix it up like we used to, and get some zones in there, but for the most part, I will be keeping my shoulders toward the line of scrimmage.”

Despite all the wonderful things the Steelers’ coaching staff and offensive linemen are saying about their intention to mix in some zone-blocking concepts this year, you’re forgiven for feeling more conflicting emotions than a pimple-faced teen.

Over the Steelers’ first three OTA practices, new offensive line coach Jack Bicknell Jr. has started to install some outside zone-blocking concepts. This new scheme will be worked into Pittsburgh’s current running repertoire, but it’ll be used with enough frequency that the concept will impact the success — or maybe lack of success — of the team’s running backs. That most notably applies to Le’Veon Bell, one of the few rookie running backs who’s in a prime position for a heavy early workload.

To put it simply, zone blocking is exactly what it sounds like: blocking an area, and not a man. To put it a little less simply and more specifically, here’s the Pittsburgh Tribune-Review’s explanation:

The outside zone blocking scheme involves the center, guard, tackle and tight end working in combination to block an area with an emphasis on double-teaming the defensive linemen who are aligned on the line of scrimmage. They will all step in unison laterally to the play side at the snap in order to create movement along the defense. The key is for the two offensive linemen working in unison to double-team the defensive lineman to decide who and when one of them will leave to block the linebacker. The running back aims for a point outside the tight end and cuts upfield wherever a seam appears. There are no predetermined holes to where a running back is supposed run.

There are two core keys to success in this system. The first is having a group of offensive linemen who are both powerful, and quick. To block a space instead of a body, they need to identify and get to said space quickly, and do so in unison. After they jettisoned some of their aging and slower bodies (Max Starks and Willie Colon), and they have highly drafted youth in the form of Maurkice Pouncey and Mike Adams, the Steelers are confident their group fits the profile.

That’s nice, and I believe them. But what about the running backs? The ideal zone-blocking running back has high-end breakaway speed, a description which certainly applies to Foster. You’d think it would apply to McFadden too, and it often does. Far more often, though, he runs too upright.

That elite straight-line speed is essential because the running back in a zone-blocking scheme needs to identify the correct seam quickly to get the edge, make one cut, and go. Preferably, go far too. Really far.

The Steelers’ running backs are fast, but they’re not Foster fast. We’re mostly concerned with Bell around these parts, because again, if the cards fall in their expected locations throughout the offseason, he has a chance to make the most significant fantasy impact. During his final year at Michigan State he finished with 1,960 total yards and 13 touchdowns, and he did it primarily by running over defenders, not around them.

However, although his style may lean more towards that of a power runner, Bell still has enough top-end speed to gain the edge and accelerate in the open field. Back at the Combine in February, Bell ran a 4.60 in the 40-yard dash, while in his draft year Foster ran a 4.69. Bell’s pre-draft scouting report at NFL.com is…encouraging:

Big, bruising back with power in his lower body but lighter feet than you’d expect give his size. North-south runner effective in one and two-back sets. Strong cuts and a nice burst out of them makes him capable of breaking off big runs when the hole is available. Sets up defenders in the open field to cut away. Flashes some stop-start ability and shake in space that freezes oncoming defenders.

And then it’s a little discouraging…

Taller back who presents a big target for defenders to hit, especially when failing to lower his pads going into the hole. Size also limits his breakaway speed and ability to create on his own if challenged by better front sevens.

North-south running is key for both a power game and behind zone-blocking. The critical difference, though, is that a running back needs to have the lateral quickness to get to the outside in a zone scheme. Bell has that, but not nearly at the same level as Foster, and likely not McFadden either.

If this was a full transition to a zone-blocking scheme, it would be a reason for caution going forward. But instead it’s a hybrid move, so we can now go about the business of being only half as worried.