Sony had been wanting rights to AEW since Day 1. Problem was WWE moving NXT to Wednesday's to compete against AEW Dynamite. Since April this year WWE moved NXT as they were failing to beat AEW in ratings. It wouldn't make sense to simulcast a similar genre at the same time.
Sony here is getting a good deal. From August AEW will have two shows Dynamite on Wednesdays and Rampage on Fridays. And their pay per views also draws huge numbers. It's a win-win for Sony as they already got Impact. The only thing that can make this deal better is rights of latest NJPW content as these companies along with NWA will work with each other. Meanwhile Eurosport only airs compilation matches of months prior.