The tyres certainly helped lotus, but track style and comparitive strength of the other cars has been the bigger factor in which car is strong where. Last year the Lotus was only particularly strong in a few races where it really looked capable of winning, most of the year it was pretty well behind the RBR, as it is now. THe Ferrari looks more capable earlier in the season than it did last year, except for a couple stupid DNF Ferrari would be way ahead of where they were last year at this stage most likely(not sure what the points difference is now tbh).
Fact is, Lotus is probably the best capable of going fast on the lower end of the pitstop scale in most tracks, its been weather more than tyre choice, and the particular track style. If Canada was much hotter, the same tyre choices for the weekend, the Lotus getting temp into their tyres and having much better tyre life than others at the front would likely have made them much more competitive.
Different tyres wouldn't have made that car better in the wet qualifying, the cars with the best tyre wear also struggle the most in cooler weather, while the cars with the worst tyre wear do their best in cooler weather. The actual choice of tyre is fairly irrelevant. If a soft and medium, Lotus do 2 or 3 stops, Merc do 4, if its medium hard, Lotus do one or 2 stops, Merc do 2 or 3 stops. Lotus are at the lower end of the scale no matter which tyres are used. The car is simply faster at some tracks than others, and in certain weather.
RBR have the most broadly fast car, its the fastest across the season on differing types of tracks, with only a couple "poor" tracks for it, more great tracks than for any other team, and most of the rest its still very competitive. Lotus are only good at a few tracks a season, Merc the same, Ferrari are closer to RBR, not many really poor tracks, plenty of decent and a few great.
