Well, Ferrari have been struggling with their downforce, so when that happens, it usually means they use-up their tires and overheat them a lot faster than cars with strong aero/downforce. In he wet, the track was a lot cooler, which meant they weren't overheating their tires. That's why when it started to dry and when everyone switched to slicks, Ferrari started to slow down... it was probably cuz they were using-up their tires more. What I haven't figured out was why Lewis was struggling even after he went on to slicks.