Posted by ESPN.com’s Bill Williamson

San Diego quarterback Philip Rivers is having a terrific season.

The Chargers would be in trouble if the passing game wasn’t working so well. San Diego is ranked last in the NFL in rushing. Rivers has plenty of help in overcoming the team’s rushing woes. Thanks to ESPN Stats & Information, here are some charts that show how important receiver Vincent Jackson and tight end Antonio Gates have been to the Chargers' air success.

Receivers targeted most on third down Player Team Tgt Rec Yds Avg TD Steve Smith NYG 35 26 301 11.6 3 Davone Bess MIA 25 19 136 7.2 0 Percy Harvin MIN 25 15 180 12.0 1 Nate Burleson SEA 25 11 154 14.0 1 Reggie Wayne IND 23 16 192 12.0 0 Randy Moss NE 23 14 183 13.1 3 Justin Gage TEN 23 6 65 10.8 0 Antonio Gates SD 22 12 195 16.3 1 Derrick Mason BAL 22 11 125 11.4 2 Dustin Keller NYJ 22 8 98 12.3 0

Most targeted tight ends Player Team Tgt Rec Yds Avg TD Dallas Clark IND 72 60 703 11.7 3 Vernon Davis SF 65 42 477 11.4 7 Antonio Gates SD 64 42 590 14.0 2 Tony Gonzalez ATL 59 38 434 11.4 4 Owen Daniels HOU 58 40 519 13.0 5 John Carlson SEA 57 33 372 11.3 2 Jason Witten DAL 56 44 391 8.9 1 Kellen Winslow TB 55 35 352 10.1 5 Brent Celek PHI 54 40 486 12.2 4 Greg Olsen CHI 51 27 286 10.6 6

Receivers ranked by times targeted 15+ yards downfield Player Team Tgt Rec Yds Avg TD Vincent Jackson SD 34 18 470 26.1 2 Steve Smith NYG 28 14 337 24.1 2 Randy Moss NE 28 13 327 25.2 2 Reggie Wayne IND 28 12 264 22.0 3 Derrick Mason BAL 25 7 198 28.3 3 Andre Johnson HOU 24 14 393 28.1 2 Donald Driver GB 24 12 299 24.9 2 Steve Smith CAR 24 10 295 29.5 1 Mohamed Massaquoi CLE 24 8 202 25.3 0