My theory, more often than not, is that most missed blowups on a frog happen for two reasons. Not saying other reasons can happen (like some here have mentioned), but most of the time it's because of two things. And I'll explain why I believe these two things.
1. The fish are too small and/or the frog is too big. If a frog is too big to fit in a fishes mouth whenever they bite, obviously they're not going to fully get it in their mouth and you won't get a good hook set. So whether its a big frog, or a small fish, this is a common issue.
2. The fish are only slapping at the frog and not trying to fully inhale it. It's no secret that a bass will smack at bait sometimes just out of reaction. They're not always trying to swallow and eat something. So when this happens, they might just be slapping at the bait to stun it, or maybe they're just nipping at the legs of the bait. Either way, you won't hook up if a fish doesn't have the full bait down in his mouth.
One thing to keep in mind about a frog - it's designed to get you bites in areas where you cannot fish other baits. So sometimes you have to accept that by its design to be totally weedless, its going to hurt its hookup ratio some, in exchange for some bites in areas that you'd never be able to fish otherwise.
Touching back on my topic #1, I came to that theory a few years back whenever I discovered a new pond nearby to me. I went once and checked it out (I found it on Google Maps). When I walked it the first time, it looked like 2 acres of frog fishing heaven. So I went back the next day with just a frog tied on and I threw that bait for nearly two hours and I had close to a dozen blowups, and not a single hookup. I went back again a few days later. Again I had half a dozen blowups and not a single fish. From then on, I decided to fish the pond using Senkos and other style baits and I quickly learned that all the fish in this pond were 10-13" long. Hence why they were probably having a hard time getting a frog in their mouth. If you've ever caught a bass this size on a normal sized frog, you'll know that a frog that size fills their entire mouth basically, so they need to engulf that bait perfectly in order for you to hook a fish that size.
Your 735c and 50lb braid is more than ample enough for frogging, so I don't believe it's your equipment.