After just over two years, the partnership between Andy Murray and coach Ivan Lendl has come to an end. In their time together, Murray overcame his grand slam demons, winning the US Open in 2012 and, of course, Wimbledon last year. Prior to these victories, Murray also won the gold medal at the 2012 Olympics.

Lendl’s impact on Murray’s career cannot be understated. Before Lendl came onto the scene, Murray was deservedly criticized for being overly passive from the baseline. He was often beat by opponents more willing to seize the moment and take their chances. Murray’s passivity would have been more readily accepted had he been a player incapable of producing high levels of offensive tennis. But this was far from the case. Murray has always had the goods, but he typically chose not to use them.

What Lendl made Murray realize was that grand slams weren’t going to be handed to him on a silver platter. Roger Federer, Rafael Nadal and Novak Djokovic weren’t winning majors by waiting for their opponents to beat themselves.

But Murray’s passivity wasn’t the only thing holding him back. His unrelenting displays of negative emotion were particularly detrimental to his progress. Beating the likes of Federer, Nadal and Djokovic is difficult enough to begin with. There have been countless occasions where Murray provided these three with unnecessary boosts of confidence with his destructive on-court attitude. Adding insult to injury, Murray’s negativity was constantly being juxtaposed to the everlasting mental resilience of Federer, Nadal, and Djokovic.

While coaches shouldn't be quick to advise a young tennis player to model their mental game off Murray’s, it is more than clear that he has made significant strides in the mental department. With this said, as of late, Murray’s negativity has been more frequent and profound coinciding with recent struggles following his comeback from back surgery.

If I’m an Andy Murray supporter, I would be seriously concerned right now. Murray has played eight tournaments since winning Wimbledon and has only reached the semifinals of one of these tournaments. In his defense, he was dealing with all of the emotions and attention that came along with winning Wimbledon. In addition, he had to cut his season short after the US Open to undergo back surgery. But now that all of this is in the rear view mirror, it doesn’t appear as if Murray has totally recovered physically and mentally from last year’s events.

And with Lendl out of the picture, Murray now enters Miami as the defending champion meaning that he has a lot at stake at a time when he isn’t playing anywhere near his best. With Lendl gone and the clay court swing on the horizon, it’ll be extremely interesting to see how Murray copes without Lendl on his weakest surface. Many wonder how many more slams Murray will win, if any. Obviously nothing is certain or set in stone, but what we can be sure of is that whoever Andy Murray hires next will have a mighty tough time filling the shoes of Ivan Lendl.