As Csfan wrote, IT repeatedly takes shots while being closely covered and doesn't move to an open place to shoot. (Okay, he does draw fouls in many cases, but it doesn't lend itself to good team play.)
IT's extremely high scoring efficiency (partly a result of drawing so many fouls) says that you are wrong.
Isaiah's ability to draw contact has resulted in a career FT/FGA ratio of .372 which understates his more current ability since he sunk charity baskets at a ridiculous .481 times per FGA rate this last Spring with Boston.
Think about that: For every 2 FGA he attempted for us last Spring, he essentially _made_ a free throw!!! Not to mention the amount of foul pressure he put on opposing players.
On the particular situation of Isaiah taking shots when "closely covered", Isaiah is very aware that most players tower over him and everyone of them think that they are going to be able to block his shot. So he takes advantage of that by instead inducing them to foul him. In truth, he got blocked on just 6.7% of his shots last year.
That is a skill. That's not 'bad shot selection'. That skill is why Isaiah has an unreal TS% (scoring efficiency) of .575 for his career.
Lamenting the tendency of this team's offense to take 'bad shots' misses the mark on why the offense has been sub par the last couple of seasons. The problem has less to do with the conditions of the shots than it is to do with who is taking the shots.
The trend in our offense has been to 'spread the offense around' so much such that too many shots are being taken by bad shooters. It is a problem that if you share shots too evenly, you are more likely to end up as a mediocre offense. Because unless you are an exceptional team, your average shooter is going to be mediocre.
The problems with the offense were, as Phosita stated, more with the fact that we had many lesser offensive players of poor efficiency taking far too many shots and not enough shots being taken by our most efficient scorers.
Evan Turner had a miserable eFG% of .451 and a miserable TS% of .481, yet he took the second most FGA on the Celtics last season. Avery Bradley posted not-as-miserable-but-not-good mediocre .490/.501 efficiencies and yet he took the MOST FGA for this team last year.
When the two players who took the most shots on your team post mediocre-to-horrible efficiency numbers, then your offense will be, at best, mediocre. And sure enough, thats what the team's offense was last year: Mediocre (18th in offensive rating).
That isn't to pick on Bradley or Turner as bad players. That's to point out that they should not be our two most prolific shooters. Just like Satch Sanders realized.