The skill lag is not getting worse because of the things in the patches themselves although maybe each new skin added the game makes for a tiny increase to server delay. Skill lag in WvW is something mainly felt in the upper tiers and is felt map wide when there are clashes of large numbers of players in one location. You can be across the map from the huge battle and still suffer your most complex skills to lag. Heals and speed boost skills seem to take more system resources than others, group buff type skills also turn into button mashers when the server is overloaded checking back and forth between way too many players at the same time. This is why you can be having a decent small fight at a camp and still be slogging thru skill delay when a huge battle is happening somewhere else on the same map. It also “feels” like once you picked up some skill delay by being in a big fight it takes awhile to wash the icky effect off your connection but I have no idea why that would be. Also, EB and the area around SM is a special kind of skill lag hell that I don’t entirely understand but battles there have always been notoriously laggy and unplayable leading some guilds to avoid that map altogether.
The reason new patches make it sometimes feel like skill lag is getting worse imo is because the WvW map population caps are dynamic and ANET has been slowly inching them up with each patch ever since they announced they were making system improvements that should be reducing these problems. I think that it began to get worse back in April after the culling fix when through.
I would love to see how the game plays now with the old WvW map population caps in place even if the insane queue’s it would cause would make me pitch a fit. I have a feeling they have actually improved a lot of the problems given that the 1/2 the map doesn’t disconnect in large battles anymore but for every improvement they make, they up the map caps a little bit as reward for themselves to be able to say “see those epic 100vs100vs100 battles we promised can happen!” but then we get a ton of skill to pay for it. I don’t think it is fair trade off. I want lower map caps that force us to spread the WvW populations out more. As it is now, people just keep transferring up to the top tiers and making the situation worse. 
People will tell you to transfer down into the bottom tiers to escape skill lag and while that is the truth, ANET is living in a fantasy land if they believe the playerbase will do what is best for themselves without some sort of incentive. Lower WvW map caps and longer queues along with one free server transfer per account and maybe another very rare way to earn server transfer contracts besides gems/gold are the only tools ANET has available to make us do the right thing and spread out.