Being in the NBA's top 50 is a pretty big deal.
To put things in perspective, being in the NBA top 50 means you're, on average, the best or the second best player on your team.
I think it's pretty clear that Jeff Green is the second best player on the Celtics right now.
Aside form Rondo, who else would be considered better? Bradley? Sullinger? Humphries? Olynyk? Wallace?
Nah. Right now Jeff Green is head and shouders above the rest as the second best player on this (admittedly not very stacked) team.
If he continues to play as well as (or better than) he did as a starter last season, then he will legitimately challenge Rondo for the #1 spot in a lot of people's minds.
One thing that I like about Green is that last season he had every excuse to throw in the towel and have a career-low year. He had to accept a bench role most of the season, he was a 3rd scoring option at best on a team which struggled most of the season, he just came back from open-heart surgery, and he already collected the security of a long term $9M/year contract extension. That's a lot of excuses for a player to sit back and slip it into cruise control, but he pushed his game to another level as soon as he got the opportunity, and it paid off in the reward of a starting role.