On what basis -- other than your well-known disdain for 4e -- are you basing the idea that WotC didn't do a good job on analyzing the math?
How about NADs?
A PC can have a NAD defense of 13 at level one (which isn't great, but isn't lousy either, 60% chance to get hit by same level foe) and because only 2 ability scores can be raised, has a 35 at level 30 (95% chance to get hit). Even with the original defense feats, that's still a 85% chance to get hit, but still a 90% or 95% against higher level foes. And yes, a player could boost that NAD a little with two level ability score increases (woo hoo, my chance to get hit dropped from 95% to 90%), but then a different NAD gets worse.
Sorry, but the entire ability score add system only allows 2 defenses out of 3 to increase at best, so it's flawed. It's still flawed today, forcing players of high level PCs to either eat the (usually multiple) feat tax, or realize that their PC is extremely vulnerable to one specific defense. The sheer size of the PHB2 NAD correction feats (combined with the fact that some of the feats stack) illustrate the magnitude of the problem.
And another aspect of the entire ability score design design flaw is that a player is doubly hosed if he wants to raise Str and Con (or Wis and Cha, or Int and Dex) on his PC. Two defenses get hosed.
Or, how about the masterwork changes on heavy armor? An obvious original math error.
Weak monster damage that had to get boosted? Combat grindiness (which was eventually corrected via Expertise and the bigger, better, badder aspect of splat book inflation) was a major problem for players the first year plus. We don't talk about grindiness too much now, but we talked about it all of the time 2 and 3 years ago.
Note: I consider Expertise to only be a minor flaw because there are other game elements that can make up for it. Some of these other flaws didn't have other core elements to help fix them.
The fact that WotC didn't fix this before release means that they probably didn't check out the math at all levels. Anyone who programs for a living knows that one has to carefully design a system and then test it out real well. 4E wasn't well designed at its fundamental combat core, nor was it well tested beyond heroic levels. The gaming community tested it out and it got bandaid-ed, mostly with feats, after the fact.
Sorry, but the core part of combat can be calculated mathematically at all levels without special PC or monster abilities added in and then adjustments can be made because of special abilities to get the desired balance with regard to number of rounds of combat, how lethal the game is, etc. I have an x% chance to hit for y average damage, so a given monster dies in z rounds. Ditto for the monster attacking my PC. Ditto for different classes and different monsters. All of that math can be done and any major issues corrected before the game is ever released.
WotC fixed "PC to hit", "PC damage" (via new class abilities, feats, powers, and items), "PC defenses", and "monster damage" over the last few years. They fixed skill challenge math twice IIRC.