Gary Marangi has the worst completion percentage in a season, at 35.3 percent in 1976.

worst completion percentage in a season
Interpreted as:
worst completion percentage with a minimum of 14 passing attempts per team game by a player in a season
1976Marangi1949Girard1966Wood1950Rote1962Davidson1955McHan1972Douglass1970Bradshaw1953Rote1960Green1947Dancewicz1944Sinkwich1968Sherman1967Tensi1971Douglass1965Parilli1945Christman1967Beathard1965McCormick1962Hadl1988Hilger1954McHan1951Rote35.335.436.137.137.137.737.938.138.939.039.139.239.840.340.440.640.640.740.741.241.241.241.4
NAMESEASONTMGPPCTCMPATTYDSAVGYDS/GTDTD%INTINT%SCKSCKYRATE
Gary MarangiGary Marangi1976BUFBUF1135.3822329984.390.773.0166.92216630.8
Jug GirardJug Girard1949GBGB1235.4621758815.073.442.3126.931.6
Dick WoodDick Wood1966MIAMIA1436.1832309934.370.941.7146.130.6
Tobin RoteTobin Rote1950GBGB1237.1832241,2315.5102.673.12410.726.7
Cotton DavidsonCotton Davidson1962TOT1437.11193211,9776.2141.272.2237.236.1
Lamar McHanLamar McHan1955CHCCHC1237.7782071,0855.290.4115.3199.234.8
Bobby DouglassBobby Douglass1972CHICHI1437.9751981,2466.389.094.5126.13217549.8
Terry BradshawTerry Bradshaw1970PITPIT1338.1832181,4106.5108.562.82411.02524230.4
Tobin RoteTobin Rote1953GBGB1238.9721851,0055.483.852.7158.132.4
Johnny GreenJohnny Green1960BUFBUF1039.0892281,2675.6126.7104.4104.454.1
Boley DancewiczBoley Dancewicz1947BOS1239.1661691,2037.1100.3116.51810.746.4
Frankie SinkwichFrankie Sinkwich1944DETDET1039.2581481,0607.2106.0128.12013.552.0
Tom ShermanTom Sherman1968BOSBOS1439.8902261,1995.385.6125.3167.145.6
Steve TensiSteve Tensi1967DENDEN1440.31313251,9155.9136.8164.9175.254.8
Bobby DouglassBobby Douglass1971CHICHI1240.4912251,1645.297.052.2156.73023537.0
Babe ParilliBabe Parilli1965BOSBOS1440.61734262,5976.1185.5184.2266.150.0
Paul ChristmanPaul Christman1945CHCCHC840.6892191,1475.2143.452.3125.542.6
Pete BeathardPete Beathard1967TOT1140.7942311,1144.8101.393.9146.143.8
John McCormickJohn McCormick1965DENDEN1440.71032531,2925.192.372.8145.543.5
John HadlJohn Hadl1962SDSD1441.21072601,6326.3116.6155.8249.243.3
Rusty HilgerRusty Hilger1988DETDET1141.21263061,5585.1141.672.3123.93125148.9
Lamar McHanLamar McHan1954CHCCHC1241.21052551,4755.8122.962.4228.632.4
Tobin RoteTobin Rote1951GBGB1241.41062561,5406.0128.3155.9207.848.6
Jim ZornJim Zorn1977SEASEA1041.41042511,6876.7168.7166.4197.6114354.3
Marlin BriscoeMarlin Briscoe1968DENDEN1141.5932241,5897.1144.5146.3135.862.9
StatMuse has season-level data for completion percentage and pass attempts per team game going back to the 1932 season.

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