I have no reason to doubt the veracity of the research in that book, but I'd point out a couple things:
1) As you acknowledged, it would be a gross understatement to point out that things have changed since 1995. In fact the very strike event that is subject was a watershed moment for MLB labor that has kicked off three decades of major gains in terms of revenue invested into player labor. Inflation since then is roughly 100%, but MLB salaries have grown at closer to 400% over the same time span. Also the internet happened, and major bumps in broadcast revenue. In the 90s, front offices had a couple dozen full-time employees, today there are a couple hundred. This is all good news -- but the reality is that the economic landscape from then to now isn't similar. I have no idea how much profit Jerry Reinsdorf, for example, was pulling in 1995, but there's a good reason he wanted to collude with all his other cronies back then, and his fear has become a reality. Player salaries are literally the majority of the operating cost today, and that's crazy when you consider the cost of operating a stadium nearly daily for six months out of the year.
2) I haven't read the book, so feel free to correct me if I'm wrong, but most of the analyses of that type I've seen over the years include asset value as part of the "losing or making money" equation. That is very important when the question is whether or not owners deserve any measure of subsidy for investment (they don't) and or whether or not we should sympathize with them when they cry poor (we shouldn't), but it's very different from the issue of annual liquid revenue, and more specifically, the ability for an org to cover significant spending increases based on team need.
I'll just reiterate that I'm not suggesting for a moment that all the owners are doing just fine and always will be. It's just important to make the distinction between the entity that owns the capital an the entity that actually makes up and runs the business. And is is critically important for ALL of us -- fans, players, employees, etc. -- that the business remain healthy, because as icky as it feels, without the business, none of this even exists.