With the influx of incoming tight ends from collegiate spread offenses, Y-ISO has become increasingly en vogue over the last five years. 

The formation consists of three wide receivers on one side of the formation and a tight end on the other side.

The isolation creates numerous coverage mismatches across the field and it can help quarterbacks identify coverage during pre-snap. 

The Kansas City Chiefs frequently used it with Travis Kelce.

“Defenses treat that formation a certain way; they have different rules for it,” Alex Smith told The MMQB. “So sometimes you can declare as soon as you break the huddle. [Travis] thinks just like I do. So he knows right away, right when we break huddle, as he’s getting up at the line he’ll be calling for things. I love when he calls ’em.”

During the 2011 regular season, the formation was used on 1,569 snaps across the NFL, according to Pro Football Focus. With each team running somewhere north of 1,000 offensive snaps per season, Y-ISO made up 5% of the average offense. Last season, in 2015, Y-ISO was used 11% of the time, league-wide.

“It’s hard to pinpoint who exactly innovated it here in the last five years, but most teams that have a tight end with some athletic ability will do it,” says Greg Cosell, executive producer of ESPN’s NFL Matchup produced by NFL Films. “It’s a big part of the NFL now.”