It worked, so everyone will praise him for the genius he is (and he is pretty damn smart, there's no question about it), but I refuse to believe that intentionally fouling a poor free throw shooter while protecting a lead late in the game is a good strategy. Let's dig into the percentages a bit.
First of all, let's examine the specific situation. Beginning with 3:15 remaining in the game and the Spurs holding a 13 point lead, Popovich had his team intentionally foul Reggie Evans each time the Clippers had the ball. A foul away from the ball in the final two minutes of the game is one free throw and the ball out of bounds, so the Spurs had about 75 seconds to use the strategy. Now before we simply conclude "Well, the Spurs won the game, so it must have been a good idea" let's bear in mind that a 13 point lead is relatively difficult to squander in a little over 3:15 regardless of your strategy. Furthermore, at the time the Clippers had scored 38 points in the preceding 29 minutes of basketball -- eight in the entire third quarter. The Spurs defense had been shutting down the Clippers offense pretty effectively, so one approach to those final minutes might have been to play defense, you know, like they'd been doing.
Evans shoots free throws at slightly better than 50%. That's for his career, for the season, and for the playoffs, so that's the number you have to use in the cost-benefit analysis. So you figure he's going to make 1 of 2 each time you foul him -- that's the expected value of that foul. That's more or less what you expect a team to score each time they have possession, so there's no real great benefit. However, each foul the Spurs fouled committed came about six seconds into the 24 second clock. Nursing a lead in the final minutes, you want the clock to run, with good reason. With their defense set, one would expect the Spurs to make the Clippers use much more than 6 seconds if they were to play solid defense.
And while the expected value of Reggie's trip to the line for two free throws is about one point, there's a slightly better than 1 in 4 chance that he'll hit both free throws. When your defense has been shutting down the Clippers for three quarters, why would you stop the clock and give the opposition a 25% chance at two points?
Reggie wound up making just 2 of 6 free throws in three Clipper possessions, but considering the percentages, he was actually more likely to make 4 of 6 than 2 of 6. Had he in fact made 4 of 6, and had Nick Young made the open three pointer he got with 80 seconds left, the Spurs lead would have dwindled from 13 to 4 in less than two minutes, thanks in part to Popovich's decision to foul.
Obviously, Reggie didn't make 4 and Young didn't make his three, but the percentages say it was as likely an outcome as the one we got. No one wants to watch the hack strategy in action -- so why would you do it when playing defense is at least as good an approach if not better?
Obviously Popovich was hedging against a hot streak, a string of three point makes, that sort of thing. But even that isn't the sure bet you might think. After all, the Clippers have been pretty successful rebounding missed free throws this season. An inverted and-one, where Reggie makes the first, misses the second, and the Clippers rebound and score, has to be considered a possibility as well.
Popovich is a very cerebral coach and is willing to undertake bold and unconventional strategies. But he was at best playing a hunch on this one -- he certainly wasn't playing the percentages. The percentages say that you give up fewer points and take more time off the clock playing standard defense for those 75 seconds. By fouling and stopping the clock, he likely gave the Clippers one extra possession if not two. And if his strategy was to avert a worst case of the Clippers making a string of three pointers during those possessions, it should be noted that he came pretty close to shaving nine points off the lead in two minutes, which would have made things very interesting indeed in the final minute.
Yes the Spurs won the game (which is the outcome you would expect when the better team has a 13 point lead with just over three minutes remaining) -- but the numbers would indicate that the Spurs won in spite of the hack strategy, not because of it.