It is not really all about offense, despite what Knicks fans and D'antoni might say. Case in point, yes offensively New York did outscore the cavs last year (105 vs 100) and yet the Knicks gave up 17 more points per game than the Cavs. They were outscored by an average of 3 per game by opponents, whereas the cavs were outscoring teams by an average of 9 points a game.
Like someone said before, who will guard Howard? they have nothing at the center position, David Lee is their only rebounder as only 1 guy on the entire team averages over 6 rebounds per game while we have 4 guys who do that on the cavs, including lebron.
The knicks give up more points, rebounds, assists, steals, turnovers, blocks, free throws, fg % than their opponents do. Even if you take off lebron from the cavs and add in the average SF performance out of a team this last year (The warriors -
http://www.hoopsstats.com/basketball/fantasy/nba/teamstats/09/8/diffeff), the cavs are only outscored by 2 (same as the Knicks), still outrebound their opponents, and lose little in the way of average blocks and steals. They do lose quite a bit in free throws, assists and assist to turnover ratio i will say that. But all that being said, that is the cavs without lebron, still generally better than the Knicks.
Also to follow up with one more point, take a look at that link above and look through the different NBA team stats and see where cleveland compares to New York. Now i didnt have time to take lebron out of all of them but even so this is pretty telling...
Backcourt, frontcourt, in and out of paint, starters, bench (which you claimed the Knicks is better), PG, SG, SF, and C. Cleveland is better in all of those. The only one they are not better in is PF, which is basically because we had Varajao and Ben Wallace playing there most of last season and your best player plays at PF. With that being said, that position is better for the knicks...by 2 SPOTS!
I hope that was reasonable enough for you...