If you want to precisely measure it, I guess, but it takes only a few moments of consideration to realize that their damage is decent until level 11, unless you are including limited resources or the -5/+10 feats. And that their AC is fairly decent compared to every class out there.
Limited resources are part of the game, so we should take them into account, making some effort to average out their impact over the course of the day.
As for AC, they likely are going from 17 to 18 over the course of tier 2. That's slightly ahead of rogues, non-Hexblade warlocks, and non-Valor bards, but that's about it (even wizards and sorcerers, who have no reason to get into melee, can sit at 16 and bump that to 21 when they need it). Warlocks and bards can take a feat, dip one level of something, or use a magical secrets pick, to boost their defenses. That has opportunity cost, to be sure, but it's at least an option. Rogues have a lower opportunity cost than monks to avoid getting attacked (either staying at range, possibly hiding, or disengaging for free), because their ability to maintain their baseline level of damage doesn't require their bonus action to the same extent that monks do, and on top of that they can halve damage from one hit per round completely at will.
Even a fighter that specs entirely for offense and invests nothing in defense except for gold (which, let's be honest, isn't a major bottleneck in most campaigns after tier 1) can usually have an 18 for most of tier 2. So monks focusing on offense are slightly behind on defense compared to other characters focused on offense... and for doing that they gain... ell, is their offensive output in that case actually on par with other offense-focused martials, even those who don't take -5/+10 feats?
Their resourceless damage is on par with that of a featless greatsword-wielding champion through tier 2, and then when you take into account the fact that champion doesn't have any resources to spend to boost that, then yes, monk comes out ahead. But that's a pretty cherry-picked comparison, because fighters level 6 feature is a bonus feat. So we should give the champion Polearm Master at least. And if we do that, the champion's at-will damage is on par with a monk who flurries every round, but they also threaten a 10' radius with opportunity attacks going in or out. Alternatively, they could trade the reach for +2 AC by taking dueling style and using a spear. It may still be about even, or maybe the monk is even a bit ahead, once you factor in the monk's subclass. But if the best you can say is that a good monk subclass is offensively about even with and defensively behind a bad fighter subclass, you haven't shown much.
What happens when a monk boosts their defense? They can spend their bonus action and ki to dodge, which functionally gives them an AC of about 21-22 on those rounds, which is on par with a fighter with a shield and the defense style,
for those rounds. But the opportunity cost they're paying to do that is higher than the fighter, because (a) that leaves the monk with that many fewer chances to stun someone, and (b) on rounds when they use their bonus action to do something other than attack, they're left doing about 2d8+10 potential damage, which is equal to a sword and board fighter who uses no resources or bonus action whatsoever, and is less than a defense fighter who uses that extra ASI they got at 6th (or who is a variant human) to pick up polearm master to do 2d6+1d4+15 with a spear or staff with no resource cost at all (if they're variant human they might have sentinel on top of that, resulting in them doing even more damage due to extra reaction attacks, and/or drawing attacks away from allies more effectively than the dodging monk).
Add the fighter's hitpoint advantage and hopefully you are starting to see why some of us are saying that defense-oriented monks are lacking in offense compared, not to offense-oriented fighters, but to defense-oriented ones.