When fast guys catch a football, they usually do fast things. Mostly, they run really far, often getting to the end of a field. That’s a little problematic for the defense, because before the end of the field is the end zone, and that’s where points are scored.

Yes, it all sounds so simple, doesn’t it? Tackling fast guys needs to happen, um, fast. Or even better, if said fast guys aren’t running backs, then preventing them from touching the ball at all is also a top priority. Oh man, why am I writing here, far away from the Ravens’ team meetings. I should be charting plans to stop Michael Crabtree, the 49ers’ fast guy whose ability to run and gain yards after the catch is consistently concerning.

Crabtree easily led the 49ers in receiving yards this year. Yep, he topped Mario Manningham by, oh, 656 yards (Crabtree finished with 1,105 yards). Those total digits aren’t exactly the kind of crooked lines that make mouths drop, but please remember that the 49ers offense wasn’t kind to wideout stat padding this year, or ever because it’s an offense rooted in the running game.

But the most important aspect of Crabtree’s skillset (quick aside: is he called “crabbie” in the locker room? Maybe “crabs”? Yeah, probably crabs) is his yards after the catch ability. Of his total receiving yardage, 465 of those yards came after the catch. That arithmetic means that YAC accounted for 42 percent of Crabtree’s overall yardage. If that doesn’t impress you, please refer back to my Falcons-49ers primer in which you were reminded that Calvin Johnson — who led the league in receiving yards — had a YAC total that accounted for only 29.5 percent of his yardage. Johnson had 859 more overall yards than Crabtree, but only 52 more YAC. Yep.

That’s what the Ravens will deal with next Sunday. A shifty, agile receiver who thrives in space while immediately adopting a punt returner’s mentality after receiving the ball. The Falcons contained Crabtree for much of the game last week (he finished with 57 yards), but he busted out in the fourth quarter for a key 33-yard reception. True to form, on his way Crabtree evaded several tackles, and stretched the reception out by 15 yards after his hands touched the football.

So how will a hard-hitting Ravens secondary fare against this particular fast dude? Welp, if I definitively knew the answer to that question, I could win all of the money in Vegas. Especially the prop bet which requires a parlay between Crabtree’s YAC, the color of Beyonce’s first outfit, and the color of the Gatorade dumped on the winning coach. But just as we did yesterday with the Ravens’ 2012 performance against mobile quarterbacks, we can ask recent history, and see what it has to say.

Crabtree finished seventh in YAC with 465 during the regular season, and there were four games when the Ravens faced a receiver who had more than him: Demaryius Thomas (512), Andre Johnson (472), and Wes Welker (619, led the league) twice. So first, the straight goods…

Targets Receptions Yards Yards/Reception
Andre Johnson (Week 7)  9  10  86  9.6
Demaryius Thomas (Week 15)  4 9 13  3.3
Wes Welker (Week 3)  8  10  142  17.8
Wes Welker (AFC championship)  8  12  117  14.6

Let’s just go ahead and call that a win against Thomas. The rest? Not so much, and there’s some concern with the two games against Welker.

Welker had catches of 24, 28, and 36 yards last week. The 24 yarder was entirely YAC, with Welker running free out of the backfield on a screen pass. Then on the longest catch — the deep ball that eventually led to Tom Brady’s crippling interception — Welker added 18 more yards of YAC. Long before that back in Week 3, Welker had a season high 59-yard reception against Baltimore, and 42 of those yards came after the catch.

Crabtree isn’t Welker in terms of his overall standing as a receiver, although if he continues to receive passes from Colin Kaepernick for a few years he may not be far behind. But as Alen Dumonjic noted last week, there’s at least one significant similarity: Crabtree’s ability to turn a simple, mundane route into a big gain.