El bastardo is easy to forget but it isn't his fault
El Bastardo had his age of dominance early in this game's development. I'm talking about the betas. He was solid during the first patches after release too but after the creation of the abomination that is reworked Makutu, El Bastardo just feels weak. Really weak. Back then people simply didn't understand what was happening and this gave El Bastardo tons of space and time to build up big shields and dish out damage all the while.
As stated in the title his percieved weakness is not his fault. He tanks by dishing out his own damage that is then returned to him as shields. The more damage he deals the more he absorbs. Simple enough. Every ability he has, including his Supers, gives him shields. Unbreakable doesn't deal damage directly and instead rewards shielding based on damage dealt during its duration as well as extending its duration as you deal damage during it (for those of you who didn't know). All of his basic abilities and his Super, Overload, are area of effect (AOE) which means he can hit multiple targets allowing him to generate more shields if he can position himself to hit multiple targets at once. It is also worth mentioning that his basic attacks have a sort of cleaving animation that makes them good for striking more than one opponent.
Normally this would be a solid hero but with Makutu in the mix he just doesn't cut it anymore (that is indeed a Machete pun). Makutu has an ocean of cc to deny El Bastardo his Death Spiral ability. Empower might generate the most shields in an instant but his Death Spiral can give him a constantly refreshing shield that can melt heroes, Kulev's totem, and Gizmo turrets simulatenously. Makutu can shut this ability down with almost his ENTIRE kit. Barge stuns, Repellent stuns, Attraction stuns, Can't Touch Us denies damage, Katamori stuns, and even his Huaki stance uppercut applies hitstun on tanks, shielded targets, and can stun heroes out of channeled abilities. El Bastardo, RIP. We all know Makutu will be nerfed soon (please be soon) but if all they do is tone down his damage while leaving his cc and Huaki stance uppercut interactions, El Bastardo will be in the same boat. He just won't be killed as quickly. Great?
Buttercup also does a great job of denying Death Spiral through her plentiful amount of stuns. Ahem. Her basic attack animation while mounted stuns, Launch stuns, yank stuns, and Burnout Stuns. The rest of the cast either has none, one, or two methods of denying El Bastardo his signature ability which is fair but means that if you want to get a Death Spiral off without being hit by a stun you are going to have to wait for many heroes to use those abilities. You almost have to use your Death Spiral to attract a stun so your allies can't get hit by those same stuns. Feels bad man.
The point I'm trying to make is: El Bastardo is over shadowed by the other tanks and he is barely a tank himself. His play style is not a problem. A mobile tank who exists to pressure the back line and dive on vulnerable targets/distract multiple enemies to quickly stack shields while trading damage effectively. He is one of the worst heroes to peel with, which normally wouldn't be a problem, but it only seems that the high level players who are communicating understand that you don't have to be a tank to peel for your allies. Even then there are still experienced players who don't seem to think/care about protecting teammates unless they are tank or support. I play primarily the damage role, I get the bloodlust, but you don't have to ignore your homies. If you decide to play El Bastardo as your team's solo tank you are essentially choosing to poorly peel for your allies or pray you can cause even damage and chaos on the opponents that your teammates survive.
Something needs to happen to give El Bastardo an assist. Most of the time I only see him succeed when he is noob stomping or playing on a team that is running another tank. At that point he might as well get shifted to the damage category and maybe get some balancing adjusted to reflect his "new" role. I don't want to see him get a rework but with the plentiful amount of cc in the tank role and a community that doesn't work well with his design I feel as if he will always be a niche pick. Not a terrible thing but it isn't a good thing either.
A bit more cc could help, a slow on Empower for example. If he reached full shields he could get a powerful but short boost: damage, movespeed, unstoppable. Maybe he could get a sudden powerful shield before he dies (on a long cooldown) to make timing a last second Unbreakable or 1UP easier.