I have to say i agree with Burna : it seems possible to control lag, using cheat processes as explained in video he posted link here.
Yesterday evening, I was leading easily a game on WT, 3-0 2-0, against a WT very common set up, 0/20/0 Gallo with 3/1 forehand/backhand.
Then, at 3rd game of 2nd set, though match had gone without any connection problem since start, big lag began. It was a really annoying lag and a very "focus" one. Indeed, it only lagged on my shots, with kind of pause just after ball came off my racket. This allowed my opponent to go to balls even when he was in difficult defensive position and, when he was in "normal" position, it allowed him to attack much more easily. At the same time, it broke my timing, which was much essential as ever for me to play correctly as my player as coach Moore in 6/0/14, which implies 46 power, then to play all balls with control shots that must be "pefect" to be efficient enough.
I eventually won that game 4-3 at 2nd set tie break but it was obvious that lag has had big impact on this game progress. I'm quite sure my opponent rose this lag voluntarly as it started at a moment he was really into big troubles (clearly, he used lag strategy too late
). Moreover, lag was always "positive" for him as it gave him more time to replace with his 43 speed player, making like my balls were slower.
I do not say that this kind of lag is the most common in TS4. Clearly not. Still, I believe that deliberate lagging can be caused.