I had some serving issues last night. I haven't played in a month, but I served the way I normally used to, and for some frustrating reason all my flat serves turned into ugly shanks. I used to get good pop on my serve, but this particular day, something was different. Even when I focused exclusively on having good form, I kept on shanking the ball for some reason (most serves went in, but there was absolutely no pop, and they were slow as well). Could it be that the ball was actually sliding on my strings?