When you watch the Portland Trail Blazers win by 30 points at San Antonio and turn around and lose two nights later to New Orleans, you always wonder why.

This is a team that beat Miami, Chicago, the Lakers, Denver, San Antonio, New York, Memphis, Indiana and Boston -- some of the better teams in the league -- and lost to the likes of New Orleans, Washington, Sacramento, Phoenix, Orlando, Cleveland, Detroit and Toronto. It seems almost impossible to explain but for a couple of things:

First, part of this is just the league itself. Scheduling leads teams into losses and wins at times in this league. You catch a team on a night when its stars are hurt and its the fourth game in five nights, it's difficult to lose. And with so many games, some nights you just can't get the job done for whatever reason. But that happens to all teams. I'm sure Miami is looking back at its loss to Portland right now and wondering what in the world happened THAT night.

But the big problem for the Trail Blazers has been constant all season: the lack of interior defense. Night after night, Portland cannot stop other teams from getting into the heart of the defense -- the paint -- and scoring. Defense, as everyone knows, is the backbone of winning teams. The offense comes and goes -- some nights you just can't make shots -- but if you're good enough on defense, you can still win.

At its core, defense is contesting shots and keeping teams away from the basket. Obviously, the closer you get to the basket, the easier the shot. Well, the Trail Blazers have been bedeviled all year by points in the paint. The Blazers are last in the league, No. 30 out of 30, in allowing points in the paint, at a whopping 46.4 points per game. And you wonder why the Blazers are looking for a shot-blocking big man? JJ Hickson isn't the answer defensively for the Trail Blazers. It's why Neil Olshey threw a free-agent offer at Roy Hibbert of Indiana last summer.

And oh, guess what? Hibbert's Pacers are No. 1 in the league in that same department, surrendering just 35 points per game in the paint.

In other defensive categories, the Blazers don't do well, either -- ranking 25th in defensive efficiency and 27th in opponent field-goal percentage.

If you want to be a consistent team, you simply must play better defense than the Trail Blazers are playing. Portland's surprising and unselfish offense bails the defense out sometimes -- particularly, it seems, against the better teams. But that's not who the Blazers really are.

It's the defense that's dragging this team into the lottery.