No, expecting Jeff to score 26 ppg. is expecting too much.
My expectations for him is 15-18 ppg while shooting efficiently (around 47% or better, around 38% or better from 3), and play great defense against opposing SF's, shooting, be a bit more aggressive on the boards and be consistent. And while everything should still run with Rondo and the pick and rolls, I also expect Jeff to be the go-to scorer if there are broken plays and no time on the shot clock and/or Rajon cant get to his spots on the floor for his shots.
Expecting him to be essentially top 5 (26 per game) in scoring asking too much IMO. Jeff Green is not a Superstar, nor I think he will, but he's a very good player who can drop buckets when needed, but certainly not carry the entire load of the scoring. If he can, then great, but let's not put a very high expectation on Green.
The rest of the points we need will then come from what Rondo makes from his shots and from the shots his teammates will get after setting them up. If Rondo is averaging 35 ppg combined with his made shots and assited baskets, then 18 ppg from Green is enough for us. The rest has to come somewhere else, whether is from Terry or someone else.