Dear god the grappler perk feels like such a trap, I knew the -10000% stagger resistance was going to make things a bit more difficult, but damn nowhere near 'The gentlest breeze is going to keep you stunlocked until the end of the match' difficult.
The problem with the perk is that the current game heavily rewards a "striker" playstyle with durable characters. Stagger resistance is king.
Going with a grappler focus makes you suffer defensively
and offensively because:
1) This game's AI is really good at dodging grabs, allowing them to punish you most of the time -- even from wakeup. Striking is risky, because so much as one jab landed on you means you'll always lose a melee exchange.
2) Lack of defensive options to compensate for the stagger resistance tax.
Blocking/parrying relies on good stagger resistance. Otherwise, you'll inevitably get guard-broken since those fast strikes add up faster than you can recover. The only alternative is playing hit-and-run with sprint and hoping the AI's dash attack (which comes out super fast with relatively good tracking) doesn't clip you. It's not as effective against opponents with high stagger resistance, though.
It's devastating when you get the grapple off, but creating those conditions is such a massive pain that grappler focus gets outshined by the others.
Edit: Tidying up some points made.