How much Tackle to take is more a function of league culture than of your own team development. These days I play in NCBB (speed-heavy league with short seasons), NBFL (very high value league), FUMBBL Ranked, and a small pickup tabletop league with a number of TT/Cyanide coaches. I don't do Slann, but I'm a big fan of 6/3/3/8 profiles, that's my kind of game. Here's where I am on Tackle from format to format.
NCBB: Too many elves. Strip is ubiquitous, and therefore so is Sure Hands. Tackle is a very high priority if you want to get yourself that ball. Slann don't have time to develop much Tackle, but just one and a lot of Wrestle is very nice.
NBFL: So much value that it would be silly not to take some Tackle (at very high TV, the ability to deal a little targeted damage is important), but 2-3 is plenty, and I've run the whole season with Zons on one Tackle (expansion team, sigh) and a ton of Wrestle, with not too much trouble. My Strip player won me a game, died, and hasn't been replaced (she would have won all the same with Tackle instead: blitzed a camping Dodge player and pow/pushed him to scoop: Tackle would have been even better).
Ranked: Speed teams tend to avoid me, no matter what I'm playing, except for rooks and legends. That said I kind of struggle vs. speed teams. I'm kind of a picker-picker: cherrypickers greenlight my Humans with their ST teams if they don't know who I am and think I'm gonna go all speed on them. I do fine with two Tackles at high value and 0-1 at low. Wrestle/Strip works pretty well in Ranked for sacking the ball (it's not for me, but it works), Tackle is for dropping hits. Elf teams need 2-3 Tackle to handle their Ranked opposition mix, unless you're like me and like to bash into bash with High Elves.
Tabletop: I take Frenzy instead, and I go all surf-o-rama on my friends. They hate it.

That or I play Halflings, and Tackle just isn't an option. I keep telling them to join FUMBBL and learn how to fight back, but they all have their excuses (mostly having to do with being unable to run the client on their computers, or not having regular access to a computer they can game on).
I know Smeborg is not really into Slann Blitzers, but having played Happygrue and watched him run a few Slann teams I've really grown to respect the Blitzer in non-matching formats. Rookie Blitzers are a bad bargain, but there are so many ways to build them, and it's not hard to get them skilled. Diving Tackle and Jump Up just combo so nicely with each other, and with so many other GAS skills, that if you can keep them alive they'll drive your opponents crazy.
Do remember though, Wrestle doesn't just deny you the AV roll, it denies you a zone on the ball, and on the erstwhile carrier. Strip allows your opponent a zone on the ball, while Tackle (when it works) denies it.
I get the power of Fend, but what I find is that Fend players die a LOT more than the same players without Fend. I guess I have a mentality of "if you got it, use it" and using Fend means doing stuff that leads to injury rolls. My NBFL Zons have decided to forgo Fend almost entirely (#4 skill for lucky linas, and maybe #4 (maybe not) for my B/G/SS Catcher @ 45 SPP), and so far I'm not in the tiniest little bit sorry. Slann, I can see how that's ever so slightly different, because you can't use Guard as anti-POMB, though Zons are very susceptible to Frenzy and T-POMB (and I have only 5 Guards anyway, one of whom is POMBing 3-4 times a match), and nevertheless I am better off without it. This might be a matter of personal tendencies, but I'm not sure: I love me some Side Step, but FUMBBL has bled all the Stand Firm and Fend out of me, taught me that my aggro playstyle leaves me no room for anything but smackdown (and Guard, lots of Guard, can't have enough).
What is Nuffle's view? Through a window, two-by-three. He peers through snake eyes.
What is Nuffle's lawn? Inches, squares, and tackle zones: Reddened blades of grass.
What is Nuffle's tree? Risk its trunk, space the branches. Touchdowns are its fruit.