What do Player Roles do? And how are they assigned?

[Shards]

Some of the player roles state that they give a boost to certain attributes in certain situations but others are very broad. I was wondering if anyone who knows can tell us what they actually do.

Also I know that player roles are evaluated and assigned in an offseason process. This process must use concrete data and there are only two real options for this in madden. Are they based on attributes and/or stats. It would seem like the most effective way to do this would be attributes.

For ratings
Example: WR with 98 or greater speed gets the Deep Threat role

For stats
Example: WR with 20 ypc it greater gets the Deep Threat role