I’m as much a fan of deep thoughts as anyone, so I was disappointed last night at Madison Square Garden when time constraints prevented me from asking Rafael Nadal, “So what, if anything, did you learn about yourself in the seven-plus months that you were off the tour?”

In a way, though, I didn’t really need to ask. At least part of the answer was written all over Nadal’s face during his exhibition match with Juan Martin del Potro, as well as afterward during his ensuing press conference. The Spaniard is really, really, really happy to be playing tennis again, despite the occasional cloud that briefly skims across his brow when he’s forced to ponder the condition of his left knee.

This may not seem like “stop the presses!” news, but in some ways you really need to be around Nadal—I mean, physically near him—to appreciate the 26-year old, 11-time Grand Slam champion’s still child-like enthusiasm for the game. At proximity, you can really feel the relish with which he competes, and even the sincerity with which he declares his passion for the game.

“For my side, all I can do now is all the right things to be ready,” Nadal said after he was beaten by del Potro, 7-6 (4), 6-4, and asked to look ahead to Indian Wells, where he’s entered to play starting this weekend.

Nadal enthusiastically chewed on the adhesive tape protecting the tips of three fingers on his left hand as he sat there, spitting out the tiny particles as he gnawed them off. Clearly, those fingers were no longer habituated to the work he’s been asking them to do. Neither, for that matter, were his knees. He suggested that the way the knees responded to the stress of playing on hard courts again would determine whether or not he would grind it out to the best of his ability in the desert.

“If the knee is not going well I cannot do anymore. But I really hope that the knee gonna go well. . . to [let me] run with no limitations—that’s a lot. That happened last week in Acapulco, for the first week [since I’ve been back]. That gave me a lot of positive feeling, a lot of confidence on myself. And at the end I am fresh mentally. I really want to keep playing. I enjoy every moment on court, and I hope I can keep doing like this.”

The words on paper, fractured and rolled out in a language not his own, don’t really do justice to Nadal’s unusual—and flat-out wonderful—marriage of realism and enthusiasm.

I confess that in recent months I’d forgotten all about that signal quality. That was partly for lack of exposure to Nadal, but also because his actions and the reports out of his camp sometimes seemed confused, just as meaningful for what they withheld as what they revealed.

It seemed at times that Nadal and his minions were obfuscating, and making his already delicate situation even more complex than it needed to be. Were they angling for sympathy? Trying to keep sponsors and potential legal issues at bay?

Now I’m inclined to think that they were just making it up as they went along, which is by no means a bad thing. Call it taking things one step at a time, in a world where everyone is supposed to have a five-year plan. But that course also requires a bit of courage, because everyone is banging on your window, demanding answers. Everyone (including yourself) is clamoring for resolution, action, and a transparency that you just can’t offer.

At some point, “We gonna see” can sound an awful lot like, “I’m not telling.”

Thus, it was truly a pleasure to behold Nadal last night, grinning like a schoolboy witnessing—never mind taking part in—his first big-time concert or sporting event. It wasn’t just when actor Ben Stiller and that cute little girl del Potro dragged out of the audience joined in to play a little crowd-pleasing doubles with the pros. And it surely wasn’t just because now and then, Rafa might have paused to ponder that he was getting a check for $1.5 million for his work on a night when he had nothing else going on anyway.

How often does the guy on the floor of the arena look like the happiest guy in the house? That was Nadal last night.

Alright, this match was an exhibition. But you wouldn’t have known it for long stretches. Nadal and del Potro didn’t even engage in one of those spontaneous, comedic episodes that distinguish exos from “official” matches until well after the Argentine had pocketed the first set. Both men took big cuts and played for the most part like the score really counted.

It’s no great insight, and it doesn’t sound like much to go on when it comes to assessing someone’s form, but how often do you really see an elite player enveloped for significant periods of time on court in what can only be described as a state of joy?

The joy will yield to concern soon enough. The last we saw of Nadal on hard courts, he was hobbling out of the Miami Masters last April, after he forfeited his semifinal to Andy Murray. Yesterday he cautioned us all not to expect too much out his return to the surface that puts the fear of God in him, and not just because of the punishment it inflict on joints like his knees.

“Remember, I am going to be playing on hard court (for the first time) after one year. Not only my knee, but my game needs to adapt to that surface. I don’t know which result I can expect from there.”

If I had to guess, I’d say he’d be deliriously happy if he just gets through it—meaning that whenever Nadal does lose, if he does at all, it will be simply because he was outplayed rather than because he broke down.

As you can imagine, Nadal has had to re-think all of his work habits because of his injury, and once he starts to put stress on the knee on hard courts again, he may need to make even more changes. To make it up as he goes along, if you will.

“I know that after seven months for my body, for my knee, for everything—I need to go slow. I’m not practicing two-and-a-half hours every day (anymore). I have to practice less. I had a fantastic week (in Acapulco) and I played one-hour-and-a-half maximum. That’s the most important thing. When you really want to play tennis, practice is important. But if you practice well, one-and-a-half hours is enough.” He smiled, quickly qualifying the thought by adding: “Maybe not when I was a kid, but now. . .”

Did Nadal really say “When I was a kid?” Forgive me for wondering when he stopped being one.