In four games, Mason leads the Ravens with 21 catches for 261 yards. The next closest receiver is WR Mark Clayton with nine receptions and 72 yards, followed by TE Todd Heap at seven catches for 78 yards. Third receiver Demetrius Williams is at six balls for 57 yards. As you can tell by those stats, Derrick Mason has quickly become Joe Flacco's security blanket.
Colts Head Coach Tony Dungy talked about the connection between Flacco and Mason in his Wednesday press call, "He's [Flacco] going to be a very, very good player for them. Right now, he has great chemistry going with (WR) Derrick Mason. He's throwing the ball well, he moves around in the pocket pretty well and he's pretty accurate."
So a young cornerback making his first start of the season against a wily veteran, who is also the rookie quarterback's favorite target, that is why Flacco might perk up when the Colts show eight in the box.
Given that, Jennings will come onto the field with a big "X" on his back. Expect Joe Flacco and the Ravens to test him early and often. Mason is an excellent underneath receiver. He knows how to get open on short routes and can pick apart zone coverage. Baltimore will go to the short and intermediate stuff all afternoon.
Jennings shows good speed and quickness over all ends of the field. He's tough but not overtly physical. Tim will slip into some bad habits, which can likely be attributed to his lack of NFL downs. For example, Jennings will get caught peering into the backfield and as a result has trouble getting a good jump on routes or will slip a step behind.
Also, Jennings will still struggle recognizing routes and get trapped flat-footed when trying to anticipate breaks. This are skills, however, I believe Jennings will improve on with more field time. But are also some things about Jennings that a disciplined route runner like Derrick Mason will seek to use to his advantage.
If the Colts decide to roll safety help over to help Jennings in an effort to take away Derrick Mason, expect Flacco to focus more on TE Todd Heap, especially downfield. Heap at TE is a better downfield threat than Mason.
If that happens, and Heap is starting to exploit the deep areas, Indianapolis will counter by showing more Cover 2 shell. Then Baltimore will go back to a heavy dose of the running game with short and intermediate passes to Mason mixed in.