Del Bonis seemed to make the jump some years ago due to his performance to the CH tour playing many qualies. But on the past years I haven´t seen him doing any improvements on his weaknesses that are his poor all around movements and footwork. Inspite of his height where he could had taken advantage of his serve he never managed to make any progress on hard court. The only improve that I found on his game is that he is serving a bit better and is attacking the ball quite more often. That is giving some results on clay but not on hard courts yet. His tennis is OK for CH tour but I don´t see him doing any damage on ATP level players yet.
His schedule organization is really lousy aswell. He didn´t write down for Santiago´s ATP where he defends QF pounts coming from quallies (57) and could had been 2nd on the alternate list (it seems that Riba is not going to play there who is the first alternate). I find it strange that he might decide to play there.
I know, i've been following his career for some years now too. Definitely was one of the many that thought he was going to make the breakthrough way earlier but, like you said, he's having trouble making his next big step forward (top 100). I think footwork and overall speed are his main weaknesses for sure but, with his power from the baseline (and how easily he generates it) + serve, IMO he is definitely ATP talent. Did you watch his match against Tipsarevic last year? A casual, non tennis fan, wouldn't have been able to tell who was the top 10 player! I'm seriously hoping he finally makes the remaining adjustments to his game in order to keep climbing up and finally leave the challengers behind. You are spot on, too, with what you say about his scheduling
it's been awful for at least a couple of seasons and I also addressed it in a thread some months ago, it's crazy how much of an impact it can have in a player's career.