Carmelo Anthony’s Tuesday night started off great. After resting for Saturday’s meeting with the Portland Trail Blazers and getting two more days off before the Oklahoma City Thunder’s next game, the future Hall of Famer looked sharp, scoring eight points in nine first-quarter minutes against the Houston Rockets to pass the legendary Jerry West to move into sole possession of 20th place on the NBA’s all-time scoring list:

Anthony kept the buckets coming in the second quarter, pouring in 11 more to pace the Thunder’s offense with 19 pre-intermission points against the West-leading Rockets.

On the other end, though? Well, on the other end, things fell apart.

To kickstart an offense that had begun the game looking sort of sluggish, the Rockets put forwards P.J. Tucker, Trevor Ariza and Luc Mbah a Moute to work, having them set screens for James Harden and Chris Paul in an attempt to draw Anthony — never a great defender in space, and now, in his 15th season, at nearly 34 years old, with nearly 40,000 NBA minutes on his odometer, an exploitable one — out and force him to defend in uncomfortable positions. Time and again, Mike D’Antoni’s club attacked Anthony, whether as a help defender tasked with rotating to stop the ball …

… or, after sticking the primary on-ball defender (mostly Paul George) with the screen and forcing Melo to switch onto either Harden or Paul, by looking to blow past him to the rim for layups, collapse the defense in the paint for kickout passes to open 3-point shooters, or force defenders to make tough choices about whether, when and how much to help off their men:

After going 9-for-22 from the field as a team in the first quarter, the Rockets shot 25-for-37 in the second and third — a blistering 67.6 percent — as they took control of the game en route to a 122-112 win. An awful lot of that damage came directly off hunting down Anthony, drawing him out into deep water, and forcing him to sink or swim. From Jonathan Feigen of the Houston Chronicle:

Melo’s capable of holding up in some of those situations and on some of those plays. He got several stops on Paul and Harden in the final few minutes, with the Thunder trying to walk the Rockets down and come back from a double-digit deficit. But a steady diet of that sort of game plan’s going to turn up quality shots more often than not.

There’s a reason Anthony ranks in just the 13th percentile in points allowed per possession when defending pick-and-roll ball-handlers, and only the 23rd percentile against roll men, according to Synergy Sports Technology’s game-tracking data. He just doesn’t have the lateral quickness anymore to consistently hold up in coverage when an opponent puts him to work in space. That’s especially dangerous against the kind of elite, spread-offense opposition — namely Houston and Golden State — that Oklahoma City will have to knock off if the Thunder are to make any real noise come the postseason, and the Rockets made him and OKC pay dearly on Tuesday.

“I mean, regardless of what a team does, we’ve been successful when we stick to what we do best,” Anthony said after the game, according to Erik Horne of The Oklahoman. “When we load up, when we help each other, when we communicate. You know, when we’re executing our defensive schemes, that’s when we’re effective, and I thought tonight we kind of got away from that a little bit, of getting away from our defensive schemes and executing defensively at times. And it hurts.”

The Thunder have been hurting a lot lately on that side of the ball. Since All-Defensive wing Andre Roberson went down for the season with a ruptured patellar tendon on Jan. 27, Oklahoma City has gone 8-9, conceding 109.2 points per 100 possessions, 21st out of 30 NBA teams in defensive efficiency, and has allowed opponents to shoot the league’s eighth-highest field-goal percentage and third-highest 3-point percentage.

That’s not to say that OKC doesn’t have the capacity to turn in excellent defensive efforts without Roberson; remember, just last month, they suffocated the Warriors in an impressive victory. You might recall, though, that Anthony played just six minutes in that game before exiting due to an ankle injury, which allowed Billy Donovan to reorient the Thunder rotation around running everything offensively through George and Russell Westbrook while rolling out younger, longer, more active wing and frontcourt players to throw at Golden State’s phalanx of shooters and drivers. The offensive ceiling of such groupings is lower than what Anthony can provide when he’s locked in. But the fit might also be cleaner: OKC’s defensive rating is nearly three points-per-100 better this season with Anthony off the floor, a trend that has largely held true in matchups against the Warriors and Rockets.

Donovan may well have some wrinkles in mind for how to best deploy Anthony defensively come the postseason when opponents try to isolate and punish him; some pre-emptive switching, perhaps, like Brad Stevens dialed up in last year’s opening round to try to keep Jimmy Butler from picking on Isaiah Thomas. Those sorts of games only last so long, though. Eventually, in the playoffs, there’s nowhere to hide. You’re out there, exposed, left to sink or swim … and if you’re not up to the task, like Anthony on Tuesday night, you can drown.

More NBA coverage:

– – – – – – –

Dan Devine is a writer and editor for Yahoo Sports. Have a tip? Email him at devine@oath.com or follow him on Twitter!

Follow @YourManDevine