No matter how long a quarterback and a wide receiver have worked together, the timing always has to be re-established. The offseason will always do that to a QB/WR duo. You have to get that going. You can do a lot of it during workouts. Just getting the feel of throwing to each other in training camp is part of it. But it is only part.
A wide receiver must get in reps with his quarterback in game situations as well. Look at all of the great quarterbacks, and how their offenses run when they run well. The timing between the quarterback and his wide receivers is nothing short of perfect. When our friend Tom Brady drops back, he knows where Wes Welker is before he even gets there. Same with the rest of his wide receivers. You can look all around the league, and it’s the same thing. How? Timing.
Mark has to get used to Santonio Holmes running routes in a game again. What routes does he like to run? Where does he like the football? How long does it take Santonio Holmes to run a 10 yard in cut, for example? These are all questions that important to answer. They are also questions that can only be answered to a point in practice. They need reps in a game. The speed is different, and playing against live opponents is different.