He's way too inconsistent...let's look at some of his losses this year
Then he beats Berdych and loses to Nadal in 3 sets, Simon in 3 sets, Istomin in 3
Then more losses to Udomchoke, Van Der Merwe, Darcis, and Amritraj before losing in a challenger F to Becker
Loses to Bozoljac, a tight loss to Simon in 2, and then he retires against Kunitsyn at Wimbledon
Then he's lost to Canas and Nikola Mektic (who is that?), and then makes a challenger F and loses to Granollers
Just a strange season
There's a trend in his losses: Grigor struggles against pushers and players with unconventional game styles. I haven't seen Ciric or Mektic play, but Ianni, Witten and especially Fischer are counterpunchers or pushers who don't do that much with the ball (though Ianni can quite easily self-destruct even with the counterpuncher game plan) and let Grigor make the mistakes. I would sort of put Udomchoke and Darcis in that category too; they are also not great shot makers. Van der Merwe and Amritraj have a serve-and-volleying game style that might unsettle him too.