Nick Castellanos didn’t run so much as he skipped, danced, leaped and floated in jubilation.

He didn’t round second base so much as he exploded it into a thousand joyous pieces.

The only thing better than Kris Bryant’s go-ahead home run in the eighth inning of Wednesday’s wild 12-11 victory against the Giants? It had to be the reaction of the teammate who was leading off at first base when Bryant connected.

For about three ridiculously fun seconds, Castellanos, 27, looked like a guy who’d sent a shot into the glorious night, Joe Carter style, to win the World Series. At the very least, he looked like someone who’d gone deep for a walk-off winner in the heat of a pennant race.

But, no, the best July 31 trade-deadline acquisition the Cubs could’ve hoped for hadn’t even delivered the big blow. He was just happy as a dog with two tails to be part of it all.

“I know, I saw that,” Bryant said. “I thought he, like, sprained his ankle or something and he was jumping because he was hurt.”

It seems Castellanos is in no mood at all to hide his sheer delight over being a Cub. Almost at the trade-deadline buzzer, he went from the worst team in baseball, the Tigers, to a postseason contender with always-engaged fans and a one-of-a-kind ballpark environment.

Must be nice.

“It’s incredible,” he said. “It really is.”

And it’s exactly what the Cubs needed. Castellanos hasn’t merely hit everything that’s moved in 20 games since joining the team. He wasn’t simply baseball’s leader with 15 extra-base hits in August entering play Thursday. He isn’t just the bopper of a hard-to-believe eight home runs as a Cub already.

He’s all that and much more. Right now, anyway, he’s the team’s emotional bellwether. Its heartbeat. Its straw that stirs the drink, if you will.

“He’s reminding us what hunger looks like,” manager Joe Maddon said. “The guy is happy to be here, obviously, to play in this ballpark, and he wants to get to the postseason badly. And I love what he’s doing.”

Castellanos, whose playoff experience amounts to three games with the Tigers in 2014, is feeling his emotions — and occasionally becoming overwhelmed by them — right out in the open. He cried this week during an appearance on The Score after listening to audio of Maddon praising his performance and personality.

“It’s easy for something that we love to get looked at like a business, you know?” he said. “I feel like that sucks, not just in baseball, but in everything in life. It just makes me feel good to hear him say that.”

Let him cry. Let him exult. Let him carry on with his somewhat confusing contention that “every day is Opening Day.” At least it sounds kind of good, whatever it means.

The Cubs will take all the positive vibes they can get.

“That’s good passion,” Anthony Rizzo said. “And this is the time of year to bring it all out.”

JUST SAYIN’

Nobody digs having Castellanos around more than Bryant. Hitting third behind Castellanos is like a golfer lining up essentially the same putt as the playing partner whose ball is sitting a few inches closer to the hole.

“I love it,” Bryant said. “We are very similar hitters, pretty close to the same swings, too, so I get a lot of information from his at-bats. And he works a lot of counts. He’s just a really professional hitter, and he’s so underrated, too. He’s definitely making a name for himself here, and we couldn’t be happier.”

For a while there, Castellanos was itching for a contract extension from the Tigers. Given those tears, one can only imagine how much a commitment from the Cubs would mean to him.

What’ll it be, Theo Epstein?

• I don’t know about you, but I could compare White Sox ace Lucas Giolito’s two best starts of the season forever without being able to figure out which was better.

Was it May 23 in Houston, when he shut out the mighty Astros on four hits, striking out nine, walking one and needing only 107 pitches?

Or was it Wednesday in Minneapolis, when he shut out the mighty Twins on three hits, striking out 12, walking nobody and digging deep for 115 pitches?

The numbers were a tad better against the Twins, but the start in Houston was when Giolito really became a man to be reckoned with.

Never mind. I’m more impressed by his 2-0 record against the Yankees this season, anyway.

• No respect. I mean, no respect at all.

All the sports books have released their college football season win totals, and the usual low expectations await both Illinois and — seriously, still? — Northwestern.

Coach Lovie Smith told the Sun-Times in a recent profile that the Illini are about to have a winning season, but the over/under for victories most books have set for Smith’s team is 4½. Those that don’t have gone even lower: 4. A reasonably decent team can roll out of bed and fare better than that.

Meanwhile, the Wildcats — who’ve merely won 15 of their last 16 Big Ten — are most commonly projected to win 6½ games. If they had most any other name on the fronts of their jerseys …

Go on, take the over on both. Free money!