Batteries have their place but aren't much use on remote islands, where the wave industry will likely have its first major gains, but undoubtedly, if remodelling were done grid-level batteries would be higher.
The research is modelled for a 30-year period and whether Carnegie or another company, the forecast is from 0.0004% global electricity to 0.28% by 2050. This is the plausible scenario, not the optimal one (which is also modelled). Keep in mind, it is about maximising emissions reductions. Coastlines are where much global energy is expended.
"Wave energy's relative immaturity [...] akin to the early wind industry. Once engineers and scientists settle on a design, the market will congeal, and prompting true competition and further adoption."
Interestingly one of the references was a Guardian article by Giles Parkinson (Renew Economy) based on a working CETO5.
https://www.drawdown.org/solutions/electricity-generation/wave-and-tidal