Thus far, these claims have been heavy on assertion and light on evidence. So, let's take a look. During Wall's two seasons with the team, the Wizards have played faster than average (top 10 in possessions per 48 minutes in each season), but they've been bad on both offense and defense.
The fact that they played faster than average and were bad on both ends of the floor doesn't really address the core issue though: Are the Wizards better when they play at a faster pace?
As it happens, I've been tracking team efficiency by pace for the past several seasons, which means I already have at my fingertips the data to answer that question. Before I do, though, I want to address the critique that I'm certain will come: that Leonsis was talking about specific players (Jan Vesely and Trevor Ariza) while I'm talking about team results.
My basic response is that a team's performance is inseparable from its players. If players like Vesely are better at a faster pace, then the team's performance should be better as well. If the team's performance isn't any better when the pace changes then it's...well...moral victory stuff to try and feel good about one guy posting better stats.
Now to the data. First, let's look at correlations. This is looking at the Wizards from Wall's two years -- 2010-11 and 2011-12. During that time the Wizards have a -0.05 correlation between offensive rating and pace; and a +0.05 correlation between defensive rating and pace. In other words, there is no correlation. In still other words, playing faster hasn't made them any better on either end of the floor.
Already, the claim is dubious. At best. Still, let's take a graphical look -- sometimes stuff pops out in charts that don't seem to show up just looking at tables of numbers.
In the chart above, the red line is the polynomial trend line for the team's defensive rating by pace; the green line is the polynomial trend line for the team's offensive rating by pace. The trend lines presented have the strongest R-squared numbers, which means I'm presenting data most favorable to the hypothesis that playing at a faster pace makes the Wizards better.
Looked at with linear trend lines, and there's a slight slope rising from left to right for both offense and defense. Which would indicate a slight tendency for the team's offensive to get a little better and for defensive efficiency to get a little worsewhen the pace slows.
Eyeballing the chart, it would appear that if pace is any factor in the team's performance, there's a "sweet spot" between 90-93 possessions per 48 minutes where the Wizards lose by a little less on average. League average pace has been about 92 possessions per 48 minutes.
But remember, the data doesn't say the Wizards should try to stick to a moderate pace. It doesn't say they should slow down or speed up. The data says that team's performance is largely unaffected by the pace it plays. The Wizards don't need to play faster or slower; they need to play better.