The reason he isn't more involved at this point is that he's been learning the same position that Jerome Simpson plays. Obviously, the Vikings weren't planning on ousting Jennings in favor of Patterson, so they taught him the playbook with Simpson's spot destined to be his. Well, Jerome has come out and been hands down the best WR on the Vikings team this season. He's made it impossible for the Vikings to bench him with his play and Patterson's snap % has suffered as a result IMO.
Simpson isn't hurt like he was last season. He knows the playbook now. Patterson threatening his job lit a huge fire under him and he is playing great. Terrific blocker last season, not sure Patterson is up to that standard yet, Jennings has not been. Webb playing more because of his blocking is something I have heard mentioned. This matters to the Vikings. Having Felton missing and then Ellison injured makes this even more important that the TE WR block well.
One of Ponders best plays statistically was off of him dumping the ball to the deep middle of the field that Simpson was amazingly able to adjust to and run down making a GREAT catch on the ball. Clearly not a pass you want your QB throwing consistently.. the QB needs to deliver a more catchable pass than this.. but nice to see a WR find a way to come down with the ball anyways. This is an area where Simpsons tremendous leaping ability comes into play. Simpson has played great. Could be even better if the QB play improves (Vikings don't play Ponder again).
Patterson is not going to beat out Jennings or Simpson playing this well and Peterson is running the ball MUCH better with Felton playing again. There will be a FB in the game often. This reduces the opportunity to play 3 WR when you are playing a FB and 1 or 2 TE. This is what the Vikings like to do. Hopefully Ellison will be back healthy soon. Zach Line hurt the running game early on. Not that he isn't a nice prospect, he is. But that hurt the running game. What does all of this have to do with Patterson? Patterson doesn't play FB. He could play tail back in diamond though. I have complained about the dud runs to Peterson out of the diamond and the throw selection (dumping over the middle out of a 9 box due to diamond?

). That can be on Ponder but I also do not like the play design. That is unless these are dead plays for scripting later on. I think Patterson can be useful as a running option out of the diamond and also on flare passes (other RB pass routes as well). I do think the Vikings will do this, they have not gotten the ball to Patterson in this way much yet though.
Better QBing may lead to more 3 WR sets. But even then Patterson has to compete/share time with Webb and Wright. This information is all contained in this thread already. Simpson playing as well as he has is an element that I didn't expect, but that is not a knock on Patterson in my opinion. Simpson has really played a lot better.
The Vikings are leading the league in kick return yardage/return right now. Patterson was also named as NFC special teams player of the month for the 1st 4 weeks of the season.
http://profootballtalk.nbcsports.com/2013/10/03/cordarrelle-pattersons-first-month-in-the-nfl-ends-with-special-teams-honors/
Cassel and Freeman are better QBs than Ponder. Freeman from what I have seen likes to throw jump balls to WR and is not shy about throwing over the middle. So I think that will be an improvement regardless of which one plays.
Freeman has a lot of velocity on his throws which will give defenses less time to track the ball. That means better efficiency on out routes as well as less time for the defense to react to throws over the middle. That should help everything. It is not like Cassel doesn't throw some scary (almost interceptions/interceptions) passes, so the turnover risk (primary concern for coaching staff with all QB) is not really worse than Cassel in my opinion, once Freemen understands the playbook and audibles similarly well to Cassel (which might not be this season). The zip on Freeman's passes might make up for the gap in understanding the offense any ways.
The Panthers are very good defense. Their main weakness is in their secondary. So I expect the Vikings to look at taking advantage of this with throws over the middle and possibly more 3 WR sets to try to get more defensive backs on the field.