(1) Jonas Jerebko is nowhere near the caliber of defender that Kenyon Martin is.
He is a tweener who doesn't have the physical power to be an above average man-to-man defender at the four or the quickness to be an above average stopper at the three. Without the capability of being a high level defensive player + lacking any resemblance of an offensive game ... Jerebko is ill-suited to a starting position in the league. If used as such, he will always be a weak player. He is all too often going to be a liability for his team. Jerebko is a 8th or 9th man utility player.
Kenyon Martin is a legitimate starting PF who was the second best defensive player in the league at his position last year. No comparison.
Jerebko I think is also gonna surprise a lot of people. Allegedly he's getting stronger. When he gets a little more cagey, if he can keep defending, and get his 3pt shot to around 37 or 38% in the next year or two, he's gonna have a pretty solid 10 year career as a top 7 rotational player.
Probably not as a starter for a contender, unless he just becomes a way better shooter and defender, but I think he'll be solid next season, fully recovered.
(2) I think J.Harden has already surpassed Kevin Martin.
Kevin Martin doesn't play defense, doesn't rebound and doesn't add anything with his passing. Until that changes, Kevin Martin is a fairly average starting two guard.
James Harden is a very good scorer (16-18ppg threat, very efficient), very good passer, good rebounder and average defender.
You and I agree on Harden.