My Okinawan Karate Sensei(who also had a Black Belt in Aikido)and I sat through a vicious storm together discussing the Aiki of Karate. Soke explained to me how Karate can employ Aiki philosophy and Aiki principles. I didn't understand and thought he was a bit crazy seeing Aiki in Karate as I guess you are seeing me being a bit crazy for seeing it in boxing. Philosophically, Aiki represents the co-ordination of mind-body-spirit into the tennents of the art. Soke said he employed it in his Karate as well. Not only philosophically but principly too. Many times when he would spar, he would try to off balance his partner and hit him when he was unbalanced. He also found it much better to avoid than block, another Aiki principle.
I watched a boxing match where a speedy quick fighter was fighting a power puncher. It was like a Shotokan stylist, linear one punch one kill, facing a Kempo fighter with multiple striking. The quicker fighter took advantage of great tai sabaki, keeping outside the boxers lead foot. He couldn't get to him with any power shots based on his use of tai sabaki. He didn't use counter punching or anything but would "body change"(tai sabaki) as some karate schools call it. The next round he uses the power of the fighter against himself. He moved in deeply(irimi) to close the range and takeaway the power shots of the power puncher. In Aikido principle you can neutralize an attack by moving irimi or tenkan. The quicker fighter employed these two principles the first two rounds to thoroughly confuse and frustrate the power puncher. Now you may think this is just a coincidence, but between rounds the trainer emphasized moving in with speed to neutralize and power to counter. This is Aiki principle at best. Also the trainer stressed to counter punch only AFTER the punch had been withdrawn. The trainer told his boxer to try and hit the power puncher in transition. I think the trainer had to have some Martial training.
Hanshi Bruce Juchnik of Kosho Ryu Kempo teaches the same thing. You counter punch when your opponenet is in neutral, not in punching mode this maximizes the punch. this is Kazushi and that is how Hanshi punches. He moves and when the person goes to punch again he is imbalanced before the second punch and strike in the transition. if you watch O'Sensei in his early days, that is exactly what he did, hit in transition. Hanshi swears its Aiki in principle. So if you would watch the whole fight you saw Aiki in motion, and if you can apply Aiki to boxing, it can be applied to anything.