A Possible Explanation For Our Struggles In Wet Weather Conditions

think it was because of the rain making the balls wet.

I completely agree with you.  My dad and I go over this everytime the weather is bad during a Michigan game.  He can't get over how soft the weather makes the team, and always goes back to the fact that "they don't play in long underwear in Florida."  I don't know about down south, but up here who doesn't get a little bit more fired up to play in a tsunami or blizzard?

Maybe.  Or how about: our offense relies on leverage and passing and generally doing stuff other than eating cheese and going GRRRR and shoving a guy backwards and when it's raining that's harder to do?  This is why people said it wouldn't survive in the Big Ten, but frankly Big Ten country isn't likelier to see rain than anywhere else.  The offense would probably struggle in a Florida monsoon just as much as a Michigan monsoon.

Plus, the later the year, the tougher the opponent, so even if there's a temperature correlation, you know what they say about causation.

they just played a mediocre game, all weather aside.

i also think that in 2008 it was our first year running the offense and then in 2009 it was our second year running the offense. 

having said that, playing in south florida in november is a  LOT different than playing in the midwest in november, as you mentioned. i think the biggest thing is experience playing in the system

I don't think it was the rain, but the giant chunks of Purdue turf that liberated themselves on every play.

Don't think rain explains much. If you look back to last year with the Capital One (PSU 19 --LSU 17), Outback (Northwestern 35 --  Auburn 37) and Gator Bowl (West Virginia 19 -- Florida State 33)...all of these were played in wet conditions. These matchups all involve teams that get mostly Northern talent and the other the reverse. There isn't a clear cut advantage that can be taken away from this. I know this is a small sample size, but the number of games Michigan has played in the RR era in the rain is also limited. I'm not The Mathlete so can't provide more robust data, this is just from a recent memory. 

Dreads absorb water, therefore in the rain the dreads are soaked with rain and heavier.  This extra weight slows us down.

solely because of rain. Crikey, what sort of pussies are they turning out in the Wingnutto State?

Was it raining during the Illinois game?

If you extend this logic you would think all teams with southern players would have problems in the rain, which may be true - I have no idea.  It would imply that an SEC game played in the rain would be a particularly sloppy, fumble-laden game.  I wonder if there are stats available on that.

In parts of FL in the autumn it can rain quite a bit, and in spurts,  suddenly stop and then be sunny and muggy as hell. Turf is wet, muddy and slippery.   I would think many of Michigan's skilled position players would be well-accustomed to wet conditions to some extent, though perhaps not wet+bone shattering cold conditions.

Also, in WV the weather can be a real bastard between September and December in terms of rain.  This didn't seem to slow down RR teams that much.

2008 was a very rainy year

I'm not sure there needs to be any complicated explanation.  This was the first rainy game of the year, and Magee, presumably in response to the conditions, called an extremely conservative game against a team cheating up to stop the run.  We DeBorded it.