It takes big guys longer to develop. Everyone said this to me when I was calling Leonar_ a bust early. You were one of them, actually. Could the same not be said about Sabonis? Age is similar, but years of NBA coaching and NBA experience are both heavily in Vonleh's favor.
Bigs do take longer (in general, there are always exceptions), but it's not about calendar time, it's about paying time. The only way to get a feel for the game is to actually play the game. The difference in actually playing time isn't that great between Sabonis and Vonleh.
Vonleh played a pretty meaningless 259 minutes of garbage time his rookie year. Sabonis as at 1415 minutes, almost all of it as a starter, and counting. He's getting way more minutes and the minutes he's getting are more meaningful (not the glorified street ball known as garbage time). By the end of his next game, Sabonis will have played more minutes is his rookie season than Vonleh played in his first two.
As far as this season goes, Sabonis is at 1415 minutes played and Vonleh is at 845 minutes.
The other thing that helps young players develop is a consistent role. Sabonis has had that, starting 64 games. As mentioned, Vonleh barely played his rookie year. Other than an a few occasional minutes of garbage time, he had no role. Last year, he went from barely playing to starting back to barely playing. That can mess with a young players confidence, which seems to be one of the things holding Vonleh back.
Same this year for Vonleh. He went from barely playing to starting. His current stretch is three games is the first time all season where he has played => 20 minutes in two straight games. He seems to finally have a consistent role and is showing significant improvement.
But, even beyond that, Vonleh is bigger, stronger, more athletic and appears to be more skilled. His wide body, big hands and long arms make him a much better rebounder than Sabonis (that's a skill I find very valuable in a power forward). Those same physical attributes also make Vonleh a better defender.
Sabonis was a good shooter (although an average 3-point shooter, at best) in college, but that hasn't translated into the NBA. That may come over time, but right now, Vonleh is a better shooter at the NBA level.
In any case, my post was in response to the assertion that Vonleh may be the worst starting PF in the NBA. He's not. He's clearly better than Domantas Sabonis TODAY. Vonleh is also better than Luke Babbit, who has started 46 games at PF for the Heat this year. In his 7th season with almost 5000 minutes played, we can't use the youth/inexperience card to explain why Babbit is worse than Vonleh. He just is.
BNM