SANTA CLARA, Calif. -- For four years with the Washington Redskins, Kyle Shanahan and Sean McVay spent many long hours talking about and building the offensive scheme and philosophies that are now so prominent on the NFL landscape.

Those conversations continued even after Shanahan left to become offensive coordinator in Cleveland and Atlanta and after McVay was promoted to replace Shanahan under Jay Gruden in Washington.

Now, as the two youngest head coaches in the NFL, Shanahan and McVay find their talks -- at least when it comes to football -- a bit more limited. Such is life when you go from bright, young offensive assistants to the head coaches of the division rival San Francisco 49ers and Los Angeles Rams.

"Any time that we cross paths at the combine or whatever it might be, we always enjoy talking ball and it doesn’t have to be anything where you’re giving your secrets away," McVay said. "But so much of what I’ve learned, it’s really, we’re operating in a very similar manner. ... I wish he wasn’t in our division and we didn’t have to play twice a year so that we could be a little bit more open with our dialogue and I feel the same way with a lot of those coaches I have close relationships with on (the 49ers staff). But, we’re fortunate to even be in these roles. So we’ll take it, but I would prefer not to have Kyle Shanahan in our division."

While Shanahan and McVay haven't coached together since Shanahan departed Washington in 2013, much of what they did there is popping up all over the league, particularly on the heels of McVay's masterful turnaround of the Rams' offense in 2017.

Shanahan and McVay's shared offensive approach actually began when each took a turn learning under Jon Gruden in their first NFL jobs in the mid-2000s. When Shanahan and McVay moved on to Washington after Mike Shanahan became head coach in 2010, it set the stage for a more free-flowing exchange of ideas. It was in those Redskins meeting rooms where many of the basic principles were refined.

Now, for anyone who closely watches the Rams and 49ers, their similarities are hard to ignore. A few calling cards -- such as the use of play-action, pre-snap motion and deceptive use of "minus" splits -- permeate both offenses. But those are smaller pieces of the larger philosophy that makes a Shanahan and McVay offense go: creating down-to-down deception while presenting the same look.

"It’s all about not creating tendencies," said running back Alfred Morris, who played for Washington under Shanahan and McVay. "It’s ‘Oh, they’ll never do this and this out of this set or this formation’ and then you try to game plan and it’s like ‘No, they actually will.’"

Coincidentally, while the Niners and Rams look the same offensively in terms of concepts, they mostly look different when it comes to personnel. The Niners favor '21' personnel, which features two running backs, a tight end and two wide receivers. The Rams prefer '11' personnel, which features one running back, one tight end and three receivers.

That's not a product of belief in either set so much as a reaction to the specific talent each team has in place. For the Niners, '21' makes sense because they have Kyle Juszczyk, one of the most versatile and dangerous fullbacks in the league. For the Rams, '11' is the easy choice because they boast a dynamic trio of wideouts in Brandin Cooks, Cooper Kupp and Robert Woods.

"It’s a key philosophy that they have offensively, and something that we’ve taken that I really learned from coach Shanahan," McVay said. "And I think when you look at successful offenses throughout the league, or people that have been doing it for a while, there’s a clear-cut identity but there’s also a level of uncertainty with regards to what’s coming next.”

Through six weeks, the 49ers offense ranks 11th in yards, ninth in passing yards per attempt and third in rushing yards per attempt. That's mostly without the services of starting quarterback Jimmy Garoppolo and No. 1 running back Jerick McKinnon, both of whom suffered season-ending ACL injuries.

In terms of deploying '21' personnel, nobody in the league is even close to San Francisco. The Niners have used the alignment on 167 of their 390 offensive snaps, easily the most in the league. They've accumulated 1,250 yards of offense from that formation, which is more than double the amount of the New England Patriots, who are second. They're also averaging nearly 11 yards per pass (sixth in NFL) and 5 yards per rush (eighth).

For the Rams, the commitment and results from '11' personnel is unmatched by any team in the league. The Rams have run 389 total snaps this season and only 16 of those plays have come from a formation that wasn't '11.' As you'd suspect, the Rams' league-leading offense has posted 2,732 yards from that set, the tops in the NFL, and is averaging the second-most yards per passing attempt and eighth most rushing yards per attempt from it.

Here, ESPN NFL analyst Matt Bowen provides a couple of examples of how the Rams and Niners run similar concepts from different formations.

Play-action is a key staple for each offense, especially on early downs. Bowen said that is often paired with pre- and post-snap movements, vertical routes from receivers lined up inside the numbers to keep the safeties in check and some sort of action that looks like an outside zone run. The idea, according to Bowen, is to pull those linebackers toward the line of scrimmage and create an opening at the second level for the quarterback to throw in rhythm.

Here's a look at Bowen's breakdowns:

Play No. 1 (Play-Action Dig Route)

Let’s start with the Rams' play-action dig concept out of 11 personnel. Using the pre-snap jet motion with the Z receiver -- while adding in the split-flow run game with the tight end (Y) blocking backside and the running back (H) on the outside zone path -- the Rams can grab the eyes of the second-level defenders. And with the slot receiver (W) pressing down the field to occupy both single-high and two-high safety sets, the backside receiver (X) can break back to the middle of the field. There is now an open void for the quarterback to deliver the ball off the play-action fake.

This is a similar play for San Francisco. This is a two-back look for the 49ers on the outside zone (or stretch) scheme with the fullback leading (F) and the running back (H) pressing to the edge. Here the 49ers add in the tight end (Y) blocking backside to create that split-flow camouflage for the defense. But the route is the same, with the X receiver occupying the top of the secondary and the Z receiver breaking to the middle of the field on the dig route. Create a void -- and expose it.

Play No. 2 (Play-Action Yankee Route)

The “Yankee” route pairs the outside vertical/post with a deep over route, or crossing route. Again, the scheme blends with both coaches, but the personnel -- and the pre/post-snap movement -- presents a different look.

With the Rams, we again see 11 personnel on the field. Here, L.A. shows the pre-snap jet motion/sweep (Z) and the split-flow outside zone play-action, as the tight end (Y) blocks backside and the running back (H) presses the edge. This will force the linebackers downhill and generate open space. Now, send the X receiver down the field on the vertical or the post to pull the cornerback with him, with the slot receiver (W) working back across the field on the over route. This is a classic zone beater that creates a clean, open window throw.

In the 49ers’ version Shanahan runs it out of 12 personnel with the same split-flow backfield look. But instead of using pre-snap jet motion, the 49ers show the post-snap wide receiver reverse (Z). And the route doesn’t change, with the X receiver clearing out and the second tight end in the game (U) running the deep over route to the void in the coverage.

When the 49ers and Rams tangle on Sunday afternoon at Levi's Stadium, it's a good bet that these plays and/or some variation of them will be dialed up at some point. And when you cut through all the fancy X's and O's, Shanahan and McVay still understand that the best coaches design what they do around their talent rather than the other way around.

"You try to get your best players on the field," Shanahan said. "That also gives you an advantage and I think they’ve done a very good job at that offensively and I think we have also.”