NPP% – Negative Pass Plays, expressed as a percentage. This is how often a team's pass plays end in either a sack or interception. The theory is that teams with poor offensive lines generally surrender more sacks (duh!) and that their quarterbacks are forced into making bad throws more often. These negative pass plays are calculated as a percentage of attempts. So if a team suffers two sacks and throws two INTs in 40 pass plays, their NPP% will be 10 percent (4/40).
3down% – Success rate on third down – the higher the percentage, the greater the offensive success and the better the offensive line.