It spouted at regular intervals nine times during our stay, the columns of boiling water being thrown from ninety to one hundred and twenty-five feet at each discharge, which lasted from fifteen to twenty minutes. We gave it the name of “Old Faithful.”-Nathan Langford on discovering “Old Faithful.”On Wednesday night, Paul Pierce scored his 23,000th point. It’s ok, don’t get up. It’s not the last thousand-point mile marker Pierce will hit, so the event was treated with a small info graphic on ESPN’s telecast of the Celtics/Mavs game. “23,000 for Pierce. 3,300ish behind Havlicek. Ho hum.”The game itself, however, was far from ho hum. The Celtics and Mavs were tied on the final possession in regulation, and Boston had the ball after Rajon Rondo successfully reached around OJ Mayo and poked the ball away. Rondo ran up the floor, failed to get around Derek Fisher and hoisted up…something. It wasn’t really a jumper or a fall-away, but it was definitely hoisted, and it definitely landed several feet short of the hoop. Overtime. The general consensus was “Ugh, a Pierce iso might have actually been better than that pile of feces.”Given the exact same situation in overtime, the Celtics, apparently thinking better of the “Let’s allow Rajon Rondo to test his newfound jumper in the biggest moment of a nationally televised game” strategy, went with the Pierce isolation option. Here’s the annoying thing: Pierce also came up several feet short on his jumper, but Dahntay Jones clearly hit him on the arm, throwing his shot out of whack. No player will ever get a foul call that late in the game, but it was a blatant foul and at any other time in the game, it would have been called. At any rate, the end result of both plays was the same, but one would be hard-pressed to make the case that Rondo’s late-game execution was as (for lack of a better term) “good” as Pierce’s.That shouldn’t come as a surprise to people who follow Pierce statistically. His detractors will claim that since this isn’t 2008, the Celtics should stop using him in isolation so much. But his statistics say otherwise. According to Synergy Sports, Pierce is 16th in the NBA in points per possession generated from isolation opportunities, at 0.94 ppp. 0.94 ppp isn’t incredibly efficient, but in late game situations, when the defense tightens up (in the good way) and the offense tightens up (in the bad way), being able to give the ball to one player and allow him to get the best possible shot is very valuable, especially when he is able to produce 0.94 ppp while doing it. The Mavericks turned the ball over on several occasions in overtime by over-passing around hyper-alert Celtic defenders which, in the end, led to Darren Collison deciding the game by panicking and throwing the ball out of bounds like a quarterback trying to kill the clock.Anyone who watches the Celtics consistently has noticed how Pierce is moving these days, and it really isn’t pretty. Yet he’s still effective. He’s 10th in the NBA in points per game at 19.9 (20.9 per 36 minutes) and 8th in Usage Percentage at 28.5, so Boston is riding him consistently. This means his efficiency is taking a rather natural hit. When plays break down, it often lands on Pierce to create something when Rondo isn’t able to do so.So how is Pierce STILL doing it? Most of the successful Pierce isolation plays start in the post, or at least with his back to the basket. By pivoting around to face the basket, he often creates enough space for himself to put up a decent, if somewhat contested jumper, like he does here against the long arms of Kevin Durant.Throughout Pierce’s career, his ability to sweep through and hit this 15-foot shot has been crucial, but now, as his athleticism wanes, it’s even more crucial since he needs that shot to be productive. Pierce’s explosiveness is nearly gone, so for several years he has had to rely on crafty footwork and ball-fakes to get to the hoop. His mid-range jumper (and opponents’ fear of his mid-range jumper) are his best bet to get a clean look at a layup.But what happens if an opponent anticipates him well? Can Pierce still score in isolation? Actually, yes. And it’s basically because, frankly, he’s a crafty old bastard.Once Pierce realizes that he has Jrue Holiday defending him, he passes back to Rondo with the intent of establishing himself with his back to the basket. As usual, he swings the ball through his motion and drives to the basket, using his bigger body to put Holiday on his hip. Holiday does the right thing (kind of) in allowing Arnett Moultrie to try to pick Pierce up, but Pierce uses his body again against the rookie and scores easily, drawing the foul. This is the other very positive aspect of Pierce in isolation: He is drawing fouls 20% of the time, which is why his true shooting percentage, .547, is so much higher than his unadjusted field goal percentage, .417.So while Pierce has been surprisingly good in isolation (not efficient, per se, but nearly as efficient as a player can be one-on-one), a look at the game tape shows that he’s been just about the same in post-up situations, which isn’t really a surprise considering that most of his success in isolation comes with his back to the basket. In post-up opportunities, Pierce is 10th in the NBA in points per possession at 0.98, and most of his post-up opportunities are almost indistinguishable from his isos. Re-watch the plays above, then take a look at this one, from Wednesday’s Dallas game.How do you differentiate between the shot against Durant and the shot against Thaddeus Young? In both, Pierce begins with his back to the basket. In both, he beats his defender one-on-one, rising for a contested two and knocking it down. The only real difference is that in plays classified as post-up opportunities, Pierce takes a couple of dribbles with his back to the basket before turning and shooting. But it’s the same kind of action. He takes his time, gets himself in rhythm and fires up a shot that he’s comfortable with, using his body to create some separation. How is Pierce still producing? Much like Kobe Bryant, he has done it by evolving and becoming one of the best players in the NBA at maneuvering in the middle-distance area on offense.“Ok,” a critic might say, “But what about defensively? You say Pierce is moving like he has cinderblocks in his shoes. How is he defending?”A quick glance is surprising. Most people generally associate a lack of athleticism with mediocre defense, but that just doesn’t seem to be the case with Pierce. According to Synergy, opponents are averaging just 0.71 PPP on 30.2% shooting from the field against Pierce. The majority of his defense has been against spot-up opportunities, where opponents are almost exactly par for the course, 0.77 PPP and 30.1% shooting, which would indicate that Pierce is closing out nicely and contesting jumpers.Against Dallas, the Celtics actually hid Pierce defensively on Dahntay Jones and (oddly) Derek Fisher on several possessions. The Fisher matchup led to several mismatches for Boston on offense, as the decaying carcass of Fisher’s usefulness really did nothing to keep Pierce off the scoreboard. These matchups make sense for Pierce. While he has put up excellent defensive stats in isolation for the season (giving up just 0.59 ppp in isolation, good for 12th in the NBA), he has struggled against players like Kevin Durant (2-4, 1 PPP) and Joe Johnson (4-8 overall). It is, of course, understandable to struggle against Durant and Johnson, both very talented players, but when Pierce’s defensive matchup can create a mismatch on the other end, there’s really no reason to make him work harder than he has too when Boston is relying so heavily on his offensive production.Examining Pierce in isolation defense is interesting in part because he is effective for all the same reasons that he is effective in isolation offensively. Here’s a matchup against Evan Turner of the Sixers:As you can see, Pierce runs Turner off the 3-point line, but he stays on his feet and with Turner as he drives, harassing Turner’s dribble. Turner gets frustrated with Pierce’s aggressive defense and shoves him off (no call), but he has been taken out of his rhythm and he bricks the shot.We have seen quite a bit of this kind of defense from Pierce. He rarely gets beat one-on-one, he rotates nicely, and he stays down on pump fakes just about as well as any defender in the NBA. An optimist would say that, as an old man, Pierce has learned everything there is to know about ball-fakes and will never bite on them. A pessimist would probably say that it’s a lot of work for an old man to jump up in the air and Pierce mostly just doesn’t have the energy for that crap anymore. A realist might split the difference between the two.It should be noted that not everything is sunny for Pierce. His 3-point percentage has regressed in each of the last three seasons, and this year is no exception, as he is down to 35% from behind the arc. Although perhaps Pierce’s most famous shot last year was an isolation 3-pointer, he is 0-4 from downtown in iso situations this year, and he is 9-27 in Off-Screen 3-pointers, feeding into a team-wide trend of struggling in Ray Allen’s old sets. But once Doc has worked those plays out of the rotation (or once Courtney Lee finds that elusive 3-point jumper that has seemingly deserted him thus far), we may see Pierce’s 3-point numbers rise a bit.More troubling have been Pierce’s percentages near the basket. He is still shooting a good percentage at the rim (62%), although his baskets have been assisted 58% of the time, the highest in his career, which indicates that he’s struggling a little bit more than usual to convert on his own. But from 10-15 feet (32%) and 3-9 feet (14%(!!!)), Pierce has seen significant dropoffs in production and consistency.What does this tell us, exactly? It’s hard to say. For much of his career, he has relied on stepbacks and drives all the way to the basket, so his low 10-15 foot percentage (step-back range) is probably more disturbing than his extremely low 3-9 foot percentage. We saw that when Dahntay Jones was able to stay with Pierce enough to foul him on Wednesday (and on any of the several step-backs Pierce missed in both of the overtime periods). It’s impossible to look at Pierce’s numbers and conclude that he’s been playing badly, but it’s equally impossible to conclude that he isn’t slipping.Paul Pierce has evolved. He’s not as good as he used to be, but he’s better at certain things than he used to be. He is Boston’s Old Faithful, as timely, consistent and reliable as anyone on the team, and we very well might find that his strengths are strong enough to keep this team above water at times when they seem to be on the verge of sinking.Here’s to 24,000, Pierce. Hope to see it soon.Follow Tom on Twitter: @Tom_NBA.