This is a timely article and relevant!! Thanks for asking the question. There are a lot of great responses. So here goes...
FWIW: After years and hundreds and hundreds of dives my my calf muscle cramps recently returned. So what changed? For me it was extensive use of my drysuit, currents, and most importantly was the moderate dehydration that was occurring before the dive. The dehydration came in terms of heat buildup while suited up, walking excessively prior to the dive sequence, cold water temps, and surface swims with doubles and deco setups. What exacerbated the situation was diving in mixed teams where some divers just wanted to dive/kick at full speed. I noticed my RMV jumped up like a 'cat pouncing on mouse' during these dives!
Anyway, so I had to rethink my physical conditioning, dive team dive partnerships, and pre-dive setup routine. I switched to layered merino wool undergarments for added flexibility and warmth. The biochemical piece came into play by striking a marriage with 100% organic coconut water (really read the labels). Then adding low sodium trace minerals, organic vinegar, adding no cramp organic solutions (the company is called trace mineral research), and iodine drops to the coco quart solution that I carry and drink the day before and between dives. Plus I switched to force fins. I added 16 x 100 yard sprints and 20 minute jump rope routines (actually a small very cool cellularsize trampoline) to my workout as well. And yes, I've always use frog kicks so that did not change other than gliding a little more.
As you can tell I took a very whole-listic approach to solving this quagmire. Anyway, good luck and think through each step and really listen to your body along the way. It took months but, in the end, we are all worth it.