This is only seeing one side of Alex. The other side is a very aggressive forward/aggressor striker that literally "mauls" guys like a polar bear on a baby seal (he was given this nickname, earned it, not chose it himself). Alex can handle being both a forward and counter-striker while Machida's specialty is a counter-striker almost exclusively. You also need to take into account that Alex's 10+ year Boxing background is going to typically translate better into the cage than Karate (of any style) will and that with their hands alone Alex is much more varied with his attacks. For instance, Alex has dropped almost every opponent he's ever fought, his KDR (knockdown rate) is very high, and this tells you a lot about his knockout ability (KO Power is just one variable encapsulated in this).
Machida will throw straights (usually straight lefts since he's a southpaw Karateka) and sometimes straight rights (when switching up stances) but beyond that he has no jab, hooks, uppercuts etc because his base is Japanese Shotokan Karate (limited hand strikes apart from chops - ridgecuts & knifehands for instance). Alex, on the other hand, has dropped or T/KO'd opponents in just his short UFC run alone thus far with every basic boxing punch there is with the exception of the overhand (which he doesn't utilize at all). He's knocked down or knocked guys out with jabs, crosses, hooks, and uppercuts (multiple times here). Machida uses his straight punches (think of it as a boxing cross but in Karateka form) and that's about it really. While Alex loves his straight punches too, he'll throw uppercuts routinely in combinations, something Machida doesn't exactly do (one punch at a time counters is about it). Alex is much more versatile when comparing their hand striking techniques and their effectiveness/knockdowns-outs.
Karate hand striking just isn't as broad as Boxing (obviously) and the varied techniques show results in Alex's favor. He has more tools with his hands alone than Machida does with his base style.
