But the difference is that with a spot foul there's no realistic opportunity for the player to calculate whether it is worth the penalty. If it's 10 yards or maybe a 45 yard catch, you will see a huge increase in PI on purpose. It is a no brainer and coaches will teach it. Holding or illegal contact doesn't make any sense as a comparison and I'm not even sure why you'd try. Holding or illegal contact makes perfect sense. Guys ARE taught to use it if they're completely burned but it's hardly used at will even though it can prevent big gainers at the expense of a 5/10 yard penalty. It's a perfectly valid comparison. And yes, of course you will see PI used as a tactic more often. I never denied that. Why is that a bad thing? Intentional fouling is a tactic used in football, basketball, soccer, etc. It's not inherently bad. It's a horrible comparison because you are talking about something done before a pass is even attempted. The payoff is not nearly the same. You don't even know who he is going to throw to, if it could be tipped or picked off, or if they might get a sack. You aren't going to use that tactic under the circumstances you would see NFL defensive backs committing a PI on purpose if it was a simple yardage penalty. And it is a bad thing because the outcomes are completely different. An intentional foul still results in free throws. A 15 yard penalty does not equate closely enough in what a potential 45 yard pass or TD pass could result in. A 10 yard penalty for holding that prevents a sack? Makes perfect sense. A safety for holding in the end zone? Perfectly fair. Pass interference that turns potential game changing plays into mere 15 yard gains is dumb. You said yourself that completing a deep ball requires pinpoint accuracy. With few guys running free and clear for easy bombs, you're not going to just commit PI at will when it's difficult to complete a bomb in the first place. There's a very realistic chance the pass won't be completed and you don't give up the 15 yards/auto first down. And presumably if these guys are capable of interfering "at will" then they're also in position to make a play on the ball or even pick it off. The idea that they are going to abandon their defensive instincts just to commit a 15 yard penalty isn't reasonable. And yes, you will see some penalties committed that would prevent obvious touchdowns or huge gains. I don't necessarily see that as a bad thing. You see at least as many horrible PI calls that unfairly give the offense huge gains under the current system.