Because people have had trouble pinpointing exactly why PCs help running, I think you will get little more than some good guesses in answer to your question.

There are several things I can think of but you don't give me enough background.

1) Are you comparing paces for similar events & similar times of year? It is January. I expect to be slower than I was in July when I peaked, but I am much faster than last January. I still run 2 hour runs slower than I would race a 5k 3 years ago, but I am much, much faster than a 2 hour run in Jan 01.
Yes I am comparing exact same races and training at the same time. Running of course is slower in Jan when not in peak.
2) 10 sec/ mile can be pretty significant. You also said that you are running the same pace after riding as you used to fresh. This is a significant change. When I do a brick on the PC's and run at Aet I can run the same speed.

3) You don't indicate how often you run. I would not expect to see improvement w/out a fair bit of running also. Usually three times a week, 1 long, 1 threshold and 1 other and possible an extra short brick here or there.

4) What is you normal cadence when you are running and is this something you work on? I think that the PCs give you leg strength to be able to increase run cadence and maintain it. But run cadence does not increase on it's own. Best method is to do high cadence stuff both on PCs and while running. I have worked on cadence and form quite a bit with the pose stuff. I am presently focusing on olympic and 1/2's I have actually lost a few pounds last year and height has not increased me race cadence is a tad higher on normal cranks then on pc's yes I have probaly pushed the bike a bit too much. $$$fact that remains on training runs with strict protocol speed has not increased any significant amount with exclusive use of pc's. This is not meant to be a criticism but an observation Joe