So...TDF is usually won by the most sneaky rider? Lol!Spot on nobody wants to ride in the front but if they are out front they don't want anyone sitting in their draft.
If a rider is leading the race and is being chased and the chasing group consists of teams of riders he will almost definitely be caught because team members take turns to chase and in a situation where it is team vs solo rider a team will win 9 out of 10 times.
However if there are no teams chasing only individual contenders for the win then he has a chance of winning even if there is someone stronger chasing from behind because the strongest rider is not going to chase with other contenders sitting on his wheel. This is why timing is everything and the strongest rider often does not win the race.