I think your on to something there. My old Jacobsen had a deck not with rollers but two small wheels that followed the contour of the ground. I could hang it up pretty easy on the front yard slope when wet. If I raised the deck a little lifting the wheels off the ground I could start moving again. My current Deere which has deck wheels but they only touch to avoid scalping has better traction. I think the reason is that half the weight of the deck is always on the drive wheels compared to tractors with the deck weight directly on the ground..... I think, by the way, that the reason there is so much tire spin is the rollers on the Simplicity tractors which cause a lot of drag on the tractor IMO....