Tillman and Jennings have led a Bears secondary that has feasted on opponents, especially on perimeter throws, defined as those delivered to targets outside the painted yard-line numbers.
2012 Passing Outside Yard-line Numbers
Jennings has seven interceptions on passes thrown outside the numbers. He has defended six other passes thrown in this area. Both marks are best in the NFL this season, according to ESPN Stats & Information.
Beyond Jennings, the rest of the Bears' defense has 11 combined picks and passes defensed outside the numbers.
As the chart shows, 49ers quarterback Alex Smith throws with very good efficiency when targeting receivers on the perimeter. His passer rating on these throws (110.3) ranks second in the NFL behind Peyton Manning (115.4). Josh Freeman (107.7), Andy Dalton (100.7), Matt Ryan (100.7), Tom Brady (94.1) and Robert Griffin III (94.1).
Smith has found tight end Vernon Davis for four touchdowns on throws outside the numbers, all in the first three weeks of the season. Mario Manningham (26) and Michael Crabtree (24) lead Davis (21) in outside-the-numbers targets. Seven of Smith's nine touchdowns on these throws came against Arizona, Buffalo and Detroit. The Seattle Seahawks held Smith to 5-of-11 passing for 57 yards, no touchdowns, one interception and a 23.7 passer rating on these throws.