As far as Lynn pitching great so far, well Kyle McClellan did pretty good for the Cardinals at the beginning of last season before he hit a wall around the All Star break and was never as good not even in the bullpen again. When you take a guy who's been pitching only relief in the majors and make a starter out of them they usually hit the wall around mid season.
The McClellan comparison last year to Lynn this year was addressed this in a different thread.
the gist was McClelllan was total smoke and mirrors and was not every close to as good as Lynn has been.
So we might think that his luck just caught up with McClellan; but Lynn has been really good (not this good, but very very good)
It is tough to make a generalization about relievers turned starters hitting walls.
There are not just that many that make that transition from full time relievers to starters. Even more so for guys that are full time relievers in the minors and the majors and then go to starting.
Looper? McClellan? and .... hard to find many
But that doesn't really fit here
Lynn has been a starter for quite a while with only 1/2 of last year in the pen
McClellan had not started regularly since 2004 in A ball. that was 7 years between starters
Also McClellan had arm injuries since he last started.