SAN DIEGO -- At some point, they’ll learn: It’s usually a bad idea to run on Fernando Tatis Jr.

Tatis made his full-time transition to right field this spring. He worked through some kinks during Spring Training, and it wasn’t always pretty. But from the moment Tatis returned from his PED suspension in April, well, there probably hasn’t been a better right fielder in baseball. 

The metrics say as much. Tatis entered play Sunday as the only corner outfielder worth at least six outs above average. He leads all players (at any position) with 13 defensive runs saved.

But forget the metrics for a second. The eye test? Holy moly, does Tatis pass the eye test in right field. Just take one look at his game-saving throw in the Padres’ 5-4 victory over the Rays on Sunday at Petco Park.

With San Diego clinging to a one-run lead in the eighth inning, Tatis came up with a brilliant 99.5 mph strike to nail Manuel Margot at home plate. It was his National League-leading seventh outfield assist of the season and the second-hardest throw on an outfield assist this year -- behind only his own 100 mph rocket on May 10 in Minnesota.

“I'm always trying to be one step ahead, anticipating that the ball was coming … and just being calm under the chaos,” Tatis said. “Just controlling what I can control and letting my talent take off.”

Calm under the chaos -- that’s an apt way to describe Tatis’ playing style. He thrives off the chaos. He practically invites it. In the Padres’ three-run third inning, it was Tatis’ aggressive baserunning that made the difference.

Then, in the eighth, he provided the game’s decisive moment, as the Padres put the finishing touches on their first winning homestand of the season and their third straight series victory, this one over the team with the Majors’ best record.

“We know we’re a good club,” said manager Bob Melvin. “We just have to play better consistently. It’s nice to take a series from these guys, as well as they’ve played this year. This game was a bit spirited down to the end. But we held on.”

That they did -- catcher Austin Nola held on, in particular. He caught Tatis’ one-hop laser and deftly applied a tag on Margot. The Rays challenged, and though replays clearly showed that Margot was out, there was some question as to whether Nola provided a lane.

“I thought it might have been blocking, I don't really know,” Nola said. “But the way the throw came in -- it was a middle-hop throw -- so with the way it came in, I figured I moved into the way just to catch the ball.”

When the umps ruled Margot out, Rays manager Kevin Cash could have no complaints -- not with the call, not with third-base coach Brady Williams’ send, not with Margot’s sound baserunning.

“Brady did right, Margot did right,” Cash said. “Unfortunately, Tatis did a little bit better.”

That was all that separated these two teams, as the Padres moved to 5-12 in one-run games with Sunday’s victory. They feel as though they’ve turned a corner lately -- and not a moment too soon with a pivotal four-game series in San Francisco looming.

“We’re playing better baseball,” said right-hander Joe Musgrove, who pitched six innings of two-run ball. “We’re being more aggressive on the basepaths. Defense, as consistent as it’s been all year. I think we’re starting to click on all cylinders now, and coming in, taking two out of three against a team like that -- it can really kickstart something.”

So here the Padres sit, within a game of .500 and playing perhaps their best baseball of the season. Notice how much rosier their outlook is than the alternative -- a series loss, another close game they let slip away.

But Tatis wouldn’t let it happen.

His wheels gave the Padres a lead. His arm ensured they kept it. His bat? He went 1-for-3 with an HBP, and he’s now slashing .400/.500/.817 this month. In case you needed a reminder of all the different ways he can win a baseball game.

More than anything, however, his defensive value has been downright stunning. The Padres thought his skill set would play nicely in the outfield. But … best right fielder in baseball? Best defender in baseball, by some measures? Who could have envisioned that? Other than Tatis, of course.

“It starts with the athleticism,” Melvin said. “And then the hard work that he’s put in from spring. You see where he’s come, with the first few balls he had in Spring Training to where he is right now. It looks like he’s been playing out there for 10 years.”