That is some very good advice they give you.
I just might add the following things I learned playing DE as my main team for a long time on and off.
*Warning, wall of text incoming*
Against CD and other bashy teams, I prefer to kick first, as defending with 11 is easier than with 8. As you saw, you need 8 players to have those nice columns. They don't need to be in a straight line but can have little bends in them to discourage switching sides from the opposition or drive them back if they do want to switch sides.
I like to pressure the cage by marking the (a) back corner(s) with a blitzer (most survivable player). If they block them, the backside of the cage is bogged down. Don't over commit as you need a good defensive line to prevent them from breaking through and a safety to plug a hole or counter attack. Typically 1 or 2 players applying pressure is enough as one elf is always capable of picking the ball up in 1 TZ dodging out and passing it down the pitch. It is also great to have a lineelf within 8 squares of the opposing Endzone. If they do suffer a Turn-over and the ball gets spilled, you can make a quick conversion. I wouldn't do it with a Blitzer, as they are too busy being safeties or annoying the ball screen.
Another thing I learned was: don't dodge just because you think you can. You only have two TRR and you shouldn't use them. Only try dodging away at the end of the turn with non key players. Sometimes it is better to leave the line-fodder on the ground until you are ready to dodge them away. Simply standing them up means more punishment for them. They can fall over failing the dodge as long as this doesn't create a hole in the line. Even a small weak spot isn't a problem if you can box them in afterwards. Sometimes this is even better as Dorfs are really slow and typically can't break through a line well.
BTW, I only started to realize that when you fail a dodge, you do risk injury but don't risk handing out SPP to the opposition. So failing a dodge is a good thing and shouldn't be RR-ed at the end of a turn
On offence I typically struggled more, as I try rushing some guys deep in the field while holding the ball deeper out of their reach. Now I know you should be playing a more running style. If your opponent does leave his backfield wide open, you should of course place a linelf there to pose a threat as receiver. Typically one player marking him is no certainty, so the chance you can pull away 2 guys from the line are real.
Now if you need a 2TTD my tactic was to spread out about 4 players in scoring position so they can't be marked easily. And also spread out 5-6 guys around the LoS. My runner with the ball just out of reach, or difficult to mark but he should be able to hand it off to different targets on the LoS. Of course you make sure your players aren't marked a lot on the line to prevent too many knock-downs.
Then you go for the pass-hand-off combination. By first blitzing/blocking a receiver free and than you pass the ball down the field. You can be amazed how much distance you can cover with this: about 17 squares easily. So it becomes clear that the Bull Centaurs should be marked, if they are still on the pitch.
The essence is that you should provide your opponent a "catch 22". If he blitzes one of your potential receivers, the runners and the guys on the LoS are free to lend a hand breaking the line. And if he goes for the runner, the receiver will easily break lose. If you do it well, there should be enough place between the lines for elves to dodge in and lend assists. This is the creating the local superiority Grievous was talking about. You only need to clear one, preferably two players to make the move work. Even if an elf is marked by one opponent he still catches the ball on a 3+, with a RR handy this has a good chance to work. So that is why you need to save those TRR, to be handy in money-time. This is after all a risky move, it typically involves at least 3x 2+ rolls, which succeeds only 58% of the time and you haven't made any dodge, GFI or block yet! So you really need that RR as all these action will be necessary to make it work.
One final advice: prepare yourself for the Dark Elf curse (meaning that you will have games that rolling a 2+ seems as difficult as dodging to a dwarf).
The best of luck, and I'm curious how it goes.
PS: can't help it but I do advise for 4 blitzers, they are that good that you will miss them if one goes off the pitch, and know that they are only 1 skill away from Blodge, even vs CD that is great tool. I also was desperate to make the assassin work for the DE but in stats he's just a vulnerable expensive Line-elf (and they are expensive for holding the line). If you only have one, he is easily marked out of the game and sadly against his main targets: fast blodgers his shadowing isn't helping much. But vs Hobgobs, he is the ideal marking man
STAB!
) are against Chaos Dwarves, both with similar builds. 
