You simply do not understand basketball is the nicest thing I can say about this post.
And you do not understand Vegas lines if you ignore them.
They've got a long history of accuracy. Billions of dollars rely upon their accuracy.
It's OK, you aren't alone. Lots of folks fail to realize defense is a team concept and you can't use plus minus with one team and equate it to playing on another.
The thought CLE will be porous defensively is rather silly. Varajao is a hard working grinder who defends.
Love is actually a good man defender and only struggles on help side defense because he is too valuable to get in foul trouble.
LeBron is an elite wing defender. So is Marion.
Irving will almost certainly be allowed to defend the easiest match up amongst guards/wings all year.
Spurs fans should be the last group needing an education in team defense after seeing Manu and Parker co-exist with a non-shot blocking Duncan yet allow fewer than 95 points for the better part of a decade.
http://fivethirtyeight.com/datalab/cleveland-cavaliers-lebron-james-kevin-love-trade-wins/
As to assets ... that's been widely discussed already. They don't need cap space to trade picks or players.
And the NBA salary cap will be going way up in 2 years anyways.
You've seen plenty of proposed trades that CLE can employ to get better. From DAL they can easily get B. Wright and R. Felton for Thompson and salary filler.
Every team has deals they can make with CLE because they have assets galore in young players and more than the normal allotment of draft picks.
CLE also has the benefit of trading for expiring guys because those players are likely to re-up to play with LeBron.