More often than not, PFF is a three-letter blunt instrument used by NFL fans and reporters to finish off a struggling player.

But enough about Matt Kalil.

What about the flip side of the dark side? What’s it like when PFF becomes a player’s BFF?

What’s it like when Pro Football Focus, the wildly popular NFL grading website, gives a player its highest grade ever at his position? When it essentially declares that angels from football heaven have descended to earth to personally knit the best safety PFF has ever graded over one entire season?

What say you, Harrison Smith, Vikings free safety and aforementioned PFF record-setter?

Smiles.

“I don’t want to say it means nothing,” said Smith, who earned a 97.0 rating on a PFF’s 100-point scale last season. “It’s sweet. But that’s not what I’m looking for. I don’t leave the field thinking, ‘I wonder what my PFF score was today!’ I worry about what Coach [Mike] Zimmer says about me fitting in the defenses that are called.”

Yes, it’s sweet when you’re sitting at 97.0 while a guy named Tom Brady weighs in at 95.5 during his third NFL MVP season. It’s sweet that no other safety rises higher than the 92 posted by Chicago’s Adrian Amos. Or when the only player who can beat a 97.0 is NFL Defensive Player of the Year Aaron Donald (99.7).

But, like a lot of us, Smith doesn’t quite understand how PFF can rule so definitively with so many nuances involved in every play.

PFF says it has a staff of more than 300 that spends about 20,000 hours grading every play by every player. Each player is graded by two analysts. Then, according to PFF, those grades are verified and adjusted, if necessary, by a network of former and current NFL coaches with more than 700 years of combined experience.

Sounds pretty doggone official. But …

“What if I completely blow a call that’s made in the huddle?” Smith said. “That’s not going to show up on tape.”

Good point. And …

“Teams play coverages differently from team to team,” Smith said. “The intricacies of every play, [PFF] just isn’t going to know how we called every play.”

We hear ya, Mr. 97.0.

PFF says Smith missed two tackles last season. Smith says that’s fake news.

“I’d say I missed more than two,” said Smith, who then raised another good point about missed tackles.

“What if you loaf when you could have gotten over and made the tackle?” he asked. “And then there are times when you shoot your gun knowing you’re going to miss the tackle, but you’re doing it to force the ball back to a teammate to make the tackle.”

Of course, last season wasn’t all PFF pats on the back for Smith. During the conference championship round, he ranked 10th out of 12 safeties when he posted a minus-1.8 rating in the 38-7 loss to Philadelphia.

“I played bad,” he said of that game. “So I’m OK with that rating.”

In the divisional playoff round the week before, he ranked 15th out of 20 safeties with a minus-0.4 rating in the win over the Saints.

“I would disagree with them on that one,” Smith said.

But it’s a new year and Smith and the NFL’s reigning No. 1-ranked defense returned to the practice field Saturday for the start of training camp at TCO Performance Center. Yes, they’re eager to start the season. No, they’re not obsessing over the Eagles beatdown.

“What happened against the Eagles?” he asked. “I feel I’ve had to answer that question a lot of times. But we just got beat. Pretty much all over the place. Period. It’s a new season.”

And PFF is locked, loaded and ready to judge.

“It’s not something I’ll go looking for, but people tweet it at me, so I do see it,” Smith said. “I just wish I would have thought of PFF first. I’ll say that much because people really seem to like this stuff.”

Mark Craig is an NFL and Vikings Insider. Twitter: @markcraigNFL E-mail: mcraig@startribune.