A lot of people talk about Green's play last season as a fluke - only scored 40 in one game, only turned it on for a short stretch, etc. But, there are a few points that leave me believing this was more than just a fluke:
The '40 point' game
It's true, Jeff Green only had one 40 point game last season. But in addition to scoring 40 against the best team in basketball, he also played suffocating defense against the best player in basketball, effectively shutting down Lebron every time he touched the ball. From memory Lebron shot something like 35% from the field on possessions in which he was guarded by Jeff Green. To score 40 against the best team in the league AND shut down the best player in the league in the very same game - even if it was only one game - is an amazing feat.
Performance as a Starter
When Tony Delk scored 50 in a game that was a one off scoring outburst - a 'fluke' if you will. Jeff Green started 17 regular season games for the Celtics last season, and in those 17 games he scored 40+ points once, 30+ points twice, 20+ points 5 times and 15+ points twice. His "Per 36" numbers over the stretch? 20.5 PPG, 6.0 RPG, 3.0 APG, 52% FG, 52% 3PT. He may not score 40 too many times in his lifetime, but for Jeff to put up good scoring numbers is not a once-off occurance.
There was a clear distinction between JG's average as a starter versus his average as a backup, where his "Per 36" numbers are a much less impressive 15.4 PPG, 4.8 RPG, 1.7 APG, 44% FG, 33% 3PT.
I believe the backup vs starter difference comes down to his playing style, which I do not feel is well suited to an "off the bench" role. A great bench scorer needs to need to be able to come off the bench cold and throw up shots without hessitation or without any conscience - you basically need to think "score" every time you touch the ball. Somebody like Jordan Crawford, Paul Pierce, Jamaal Crawford or James Harden (in OKC days) is a perfect example of that guys who could excel in a "scorer off the bench" role.
Jeff Green doesn't really have that type of mentality though. Like KG, JG seems to be more of a passive style of offensive player who likes to let the offense come to him. Like KG in his prime, Jeff will still get his points over the course of a 35-40 minute game simply because he is too good a scorer not to. However, if you're only throwing him out there for 25 minutes a night (in 6 minute blocks) then a player like Green probably won't have enough time out there to get comfortable and get in to a rythm.
I really believe that Jeff Green is at his best offensively when he is starting and playing 35+ minutes per night, because this scenario gives him the time to get comfort zone and find those scoring opportunities. Once he does get comfortable and gerts in the zone he is capable of exploding for 15 points in 8 minutes and is more than capable of being a 20+ PPG scorer.
Performance in big moments
During the season Jeff hit multiple game winners. He also was Boston's best scorer (averaging over 20 PPG) in Boston's playoff series against the Knicks. Finally, Jeff has put up some incredible defensive performances against some of the leagues most elite small forwards - Lebron James, Kevin Durant and Carmello Anthony are just a few guys that Jeff has effectively shut down on the defensive end in matchups. All of this tells me that JG is not afraid of the big moment - if anything he seems to have a tendancy to elevate his game to another level when on the big stage. This is one of the key attributes that separates a star player from a 'good' player - the ability to excel under extreme pressure. It's a fairly small sample size, but last year Jeff showed me that he has the ability to step in to that role, and that to me is a great sign.
Of course I'm not saying Jeff Green is going to explode for 29 PPG, win DPOTY and take over Lebron as the best player in the NBA. All I'm saying is that, from what I've seen so far, he has the ability to be a very good player and borderline All-Star. I think 17/5/2.5 (just under Paul George numbers) is his absolute worst case, while an absolute best case of 23/7/3 is not outside of the realm of possibility.