Anyone who has followed the mythology of the Kyle Shanahan offense over the years knows both what is capable of, and provided by, a legitimate ‘X’ wide receiver. Coaches who have worked in that system deify both game-altering speed (see former Shanahan assistant Klint Kubiak pushing to bring Rashid Shaheed to the Seahawks last year, or Mike McDaniel building his Dolphins roster with Tyreek Hill and Jaylen Waddle) or to alter the course of a game as a large-bodied, physically dominant, alpha-type wide receiver.

Shanahan has crossed paths, and maximized his tenures, with both Julio Jones in Atlanta and Andre Johnson in Houston. The issue with these wide receivers is that they simply do not come around—or come available—all that often.

So begins the hype prologue for Mike Evans joining the 49ers, a move that, assuming health (always a dangerous proposition for a soon-to-be-33-year-old wide receiver) will have the largest single impact of any signing this year in free agency and be able to return the 49ers to a pedestal example of offensive efficiency.

The tentacles of this move, outside of Evans feeling schematically dried up in Tampa Bay and seeking new challenges, are vast.

First, this is a clear indication that Shanahan saw the Rams’ move for Davante Adams before last season and wanted to create a similar dynamic. While Shanahan has succeeded with big ‘X’-style wide receivers, he has not, of late, lined up a ton of receivers like Evans. It will likely signal something of a stylistic change from the most recent 49ers offense as we knew it. While this isn’t an attempt to mirror L.A.’s setup—Puka Nacua earned Adams a lot of single coverage reps, which Adams tends to dominate, while it’s uncertain how much help Evans will get from Ricky Pearsall—it is an alternate path to a similar end.

Second, Evans is the best wide receiver in the NFL against man coverage and, like Adams, will dominate if Shanahan is able to scheme the defense into man tendencies. The 49ers, with their amoebic personnel, have set the modern standard for how an offense can dictate the personnel of a defense. However, some who have coached in the Shanahan system believe this move will have its largest impact in the running game. Evans is certain to draw a lot of double teams—he was sixth last year with a 35% double-team rate—which means he’ll draw safety help away from the running game. Lately, teams have been committing that additional safety to Christian McCaffrey, which helps explain the grind-it-out nature of McCaffrey’s rushing output last season (McCaffrey had one of the highest percentages of eight-man boxes in the NFL last year, at nearly 30%).