Thats how Maria tends to be, though, dont you think? Shes an amazing tennis player in many ways, but she has her off days, and shes also susceptible to certain types of playersboth of which can add up to some bad results if she isnt especially sharp.
So, for me, dips like we saw earlier this yearin Indian Wells and Miami, for instanceare almost inevitable. If she can catch fire and be sharp for one or two GS seasons per year, though (like she was during her run to the French a couple of years ago), she should be able to grab a few more GS titles before she calls it a day like Pennetta.
As for Halep, I still like her and I still think shes going to win a few (at least) GS titles in her career, but shes going to need to work on the mental side of her gameand quickif thats going to happen anytime soon. At the moment, though, she pretty much always falters when confronted with a big moment, which has to be worrying.
Also, even though shes got to be comforted by the fact that Serena and Maria and other big hitters are in the twilight of the careers, were already seeing some younger playerslike Muguruza, Bencic, maybe Bouchard if she can ever get her act together again--step forward as candidates to take their place, and some or all of those replacements could keep Halep from winning some/any GS titles down the road.