KG's career has been cut short by injuries.
Without injuries probably, maybe, perhaps KG.
With injuries Dirk.
KG hasn't aged as well and didn't ever have the offensive repertoire that he could have. That knee injury took away his 2nd and 3rd rings and left him hobbled and 1/2 the player he was before.
Cut short by injuries? Hasn't aged well? What? 
He's in his 20th season, was an All-Star in his 18th season, and All-NBA Defense in his 17th season, and will probably finish this season 3rd all time in minutes and 5th or 6th all time in games played.
KG has actually aged pretty well and his career was not cut short by injuries. In fact he's had one of the longest careers of anybody ever.
(Not that Dirk also hasn't had a nice long career, but let's see how he's performing in his 19th and 20th seasons).
It's probably safe to say that KG's tenure with the Celtics was certainly undercut by injuries.
Everyone's career ends from and is affected by injuries, usually way before KG's age. KG has had a remarkably healthy career.
His '08-09 injury probably cost the Celtics a very legit chance at a 3 Peat. With a healthy KG, that '09 team is cruising to the Finals and with a health KG instead of a limping KG, he's not getting manhandled by Gasol in the '10 Finals.
Has everyone forgotten just how dominant the Cavs were that year? I don't think that we could have beaten them without homecourt, and even then, it would have been a toss-up at best. They embarrassed us twice in Cleveland, once without KG, but to suggest that it would have been a walk in the park for us to get to the finals is quite ridiculous, imo. The Cavs wanted us, we no longer had Posey, and Leon went down (which may or may not have happened depending on if Garnett didn't get hurt). Even if Rondo played the way he did when KG was hurt in the playoffs with a healthy Garnett (sorry, I know that I've written this rather poorly), I don't think that we would have gotten out of the east, and even if we'd had, the Lakers would've beaten us, because, again, WE HAD NO DEPTH. Thanks Danny (sarcasm)!
The Cavs finished a few games ahead of us because KG missed about 1/3 of the season with a knee injury. The Cavs were easily beaten by a Magic team that was close to even with the KG-less Celts. The Cavs wouldn't have posed that much of a problem in the playoffs.
That's because Orlando presented so many mathup problems for Cleveland, especially between Howard, who was so much faster, stronger, and quicker than Big Z, Varejao, or Joe Smith (Ben Wallace wasn't playing the role that he had early in the season due to a significant injury), and Rashard Lewis. None of the said Cavs big guys were quick enough to stay with him off the dribble or recover in a pick and roll, and, to make matters worse (not that I feel sorry for Cleveland lol), none of those guys could attack him because the major contributors in Z and Floppy were never post players. I really think that you guys should go back and look over that series. Something tells me you're viewing such a time with much more of a positive outlook than was felt at the time lol.
I don't think they'd have fared tremendously better against KG than they did against the Magic's bigs. We didn't have Posey, but Rondo was significantly better in the 2009 playoffs than the 2008 playoffs, Baby was better, and we had the all-important playoff/championship experience. You're selling the team short by a lot.
It wasn't about their offensive production, though. It had everything to do with their complete and utter inability to guard Rashard Lewis and Howard. They were practically nonexistent, offensively, and the 3 point shooting of the Magic gave guys like Dwight and Rafer Alston so much more space than we could have ever presented Cleveland with in terms of matchup problems. It also doesn't help our cause that Ray Allen never developed a post up game aside from a lame fallaway that would have allowed us to take advantage of the small size of Cleveland's guards. The bottom line, though, is that we simply didn't have enough that year.
Why are you hate Ray Allen? It's sad that you clamor for Joe I don't give... Johnson. Just for your information Ray was more recognized than Pierce around the NBA before he was traded to the celtics, he sacrificed the most of the big 3. Just in case if you are a celtics homer nba fan.
BTW With healthy KG the path is clear to the NBA finals in 2009.
I'm well aware of how much Ray sacrificed, but who cares if he was known more, nationally, than Pierce? Just because a guy gets a ton of endorsements and other stuff doesn't mean that he's better than a guy like Michael Redd, who had a post game lol, or Pierce, it just means that some companies wanted to affiliate themselves with him. Guys like Pierce, Redd, and Joe Johnson are/were ignored and grossly underrated for much of their careers, but that doesn't mean that they were automatically inferior to Ray, Kobe, TMac, Vince, etc.
You don't think that Joe Johnson would have been better, on both ends, than Ray, with KG, Pierce, and Rondo? I'm sure that we could argue about that til the cows come home lol, but purely in terms of size, having another guy as big and strong as Pierce definitely would have made a big difference defensively against guys like Lebron because Pierce was almost always reffed out of the games against James, especially in the postseason. I guess that I just view Ray differently because of how he left, and so that will always tarnish his time here, unfortunately, for me. Yes, Danny's an idiot for always trying to trade him, but Pierce and KG stepped in and prevented him from going to somewhere like Detroit, Sacramento, or Memphis, and I just think that, if you're not going to stay for Danny, and if you're not going to stay for Doc, you should at least stay for your teammates, never mind the fans, who adored you here for close to 20 years.
It's fine to disagree with me, but I just don't think that the path back to the Finals would have been nearly as easy as you guys are portraying it.