the way i see it, the level of control shown every year by USPS was unnecessary.
if as a GC contender you decide that only position/jersey matters at the final standing and are prepared to lose the jersey in the first couple of weeks then the workload on your team is greatly reduced.
the first hour (or so) is very hard, as they ensure that only the right break goes up the road. cant be big enough to put 30 mins (against team wishes) or time for a favorite.
got to be able to chase back after a mech and keep leader fed.
TTT must be competent.
in the mountains team must be able to slim peleton to size where rivals don't have enough help to put your leader under pressure.
basically, if you deliver your leader to last climb with the group of 10 favourites and no favourites up the road and not many domestiques left. job done.
for AC, IB and AS they all have strong enough teams to do that and once the big boys start going toe to toe on mountains there won't be help around.
(if GC hope pops, it's nice to have someone pace them)
basically, all of the hopes have teams strong enough to let them win if they're the strongest in the race. If you're fourth strongest and have the best team, you'll still need to get lucky.