Can you explain this? I am confused. Maybe they have 13 personnel on the field, but with the flexibility of the tight-ends, they line up in a 11 personnel formation? I'm interested in understanding this approach which is why I am asking.
Yeah, no prob. Basically, I'm conflating personnel and formation/plays run from them. This happens in the media and stuff - part of the reason why is we have so many hybrid players in todays NFL (think move TEs who are glorified slot WRs).
For this discussion it's better to think of personnel as just the type of players but it is predictive of the kinda plays you'll run.
13 personnel is three tight ends, 1 RB and a WR. Generally, a lot of plays from 13P are run from formations that have one TE lined next to a tackle and the other two TEs on his wing or offset. You tend to run running plays from this formation. The Rams will often align their TEs not only in this formation but in the typical formations they run from 11P. Think trips WR stacked near the tackle or the more traditional 11P formation of X on the boundary (Fergy split out), slot WR (Allen in the slot), a Y TE (Parkinson next to the tackle) and Z receiver (okay they didn't run this exact formation to my knowledge but I'm using it as an example as it's too complicated to describe the motion and condensed formations the Rams typically run from 11P but I think you get the drift.)
Now any team can line up in a formation like that with any personnel they want but what makes the Rams so dangerous in 13P is that they can run a lot of the same plays from these formations they would normally run with 11P. Guys like Allen and Fergy offer the athleticism to either stretch the field (Fergy) or sink their hips to get in and out of faster cutting routes (like Allen) and offer the ability to block (which a lot of TE's struggle with these days). One of the reasons we were able to pivot to 13P due to injury and not just get bogged down is that we have TEs that can run the in breaking routes from the X or Z receiver spot, out and ups, option routes.
Basically, we didn't change much from our playbook we just used the different players. Other teams with less dynamic TEs who struggle to block, or can only run an even more limited route tree then our own due to lack of athleticism just won't be able to run the breadth of plays we're able to from 13P and probably will have to run plays that require their own unique install which will bog down their offenses.
Does any of this make sense?