But the accomplishments he listed (e.g., having a strategic plan, website redesign) are of the type that Holden already indicated to be inadequate. So why the exhaustive listing, instead of just giving a few examples to show SI is getting better and then either agreeing that they're not yet up to par, or giving an argument for why Holden is wrong?

Presume that SI is basically honest and well-meaning, but possibly self-deluded. In other words, they won't outright lie to you, but they may genuinely believe that they're doing better than they really are, and cherry-pick evidence without realizing that they're doing so. How should their claims of intending to get better be evaluated?

Saying "we're going to do things better in the future" is some evidence about SI intending to do better, but rather weak evidence, since talk is cheap and it's easy to keep thinking that you're really going to do better soon but there's this one other thing that needs to be done first and we'll get started on the actual improvements tomorrow, honest.

Saying "we're going to do things better in the future, and we've fixed these three things so far" is stronger evidence, since it shows that you've already began fixing problems and might keep up with it. But it's still easy to make a few improvements and then stop. There are far more people who try to get on a diet, follow it for a while and then quit than there are people who actually diet for as long as they initially intended to do.

Saying "we're going to do things better in the future, and here's the list of 18 improvements that we've implemented so far" is much stronger evidence than either of the two above, since it shows that you've spent a considerable amount of effort on improvements over an extended period of time, enough to presume that you actually care deeply about this and will keep up with it.

I don't have a cite at hand, but it's been my impression that in a variety of fields, having maintained an activity for longer than some threshold amount of time is a far stronger predictor of keeping up with it than having maintained it for a shorter time. E.g. many people have thought about writing a novel and many people have written the first five pages of a novel. But when considering the probability of finishing, the difference between the person who's written the first 5 pages and the person who's written the first 50 pages is much bigger than the difference between the person who's written the first 100 pages and the person who's written the first 150 pages.

There's a big difference between managing some performance once, and managing sustained performance over an extended period of time. Luke's comment is far stronger evidence of SI managing sustained improvements over an extended period of time than a comment just giving a few examples of improvement.

I've added a clarifying remark at the end of this comment and another at the end of this comment.