In 2015, the Raptors have a losing record (13-14). What better way to get back up to .500 this year than a trip over to Philly? Yeah, the opening paragraph is in no way intended to comfort you. Actually, it’s probably worse than you initially thought.
In their fourth road game in five nights, the Toronto Raptors ran out of gas in the the fourth quarter and the Dallas Mavericks jumped all over them. Dallas would come back from nine down to win, 99-92.
This I can explain. His low usage rate when he is on the floor minimize his impact on team stats, such as team O/D rating and even plus minus (since that stat also accounts for the other members of the rotation. However, when he is being used, his individual stats, or the stats that are only dependant on his contributions, he looks pretty good, pretty great even.
Basically, like what everyone else has been saying, it comes down to usage rate. Involve him enough in the offense and there's no reason why his individual efficiency won't be reflected in the team stats.
Now here's where you might say "but the raptors lose more when he shoots more than average, so the usage rate argument doesn't hold up". That's a fair point, but I would argue that Jonas often gets those extra field goals when A) the guards are putting up a ton of bricks and Jonas is cleaning the glass, or B) he's a last resort after its clear that the other scoring options aren't working. In both scenarios, the team as a whole is playing below average, so it makes sense that they would win a lower percentage of games.