That's when I decided to go back through the Space Wolves Codex and think about units, characters, HQ choices, and vehicles and ask the question: why not use them?
The very first unit in the book are the Blood Claws and they rarely get to see the battlefield due to the fact that their Older Brothers do what they do and are better at it. Blood Claws are 1 less WS and BS than the Grey Hunters, lose the Bolter that their older brothers have, lose access to the Wolf Standard, lose access to the Mark of the Wulfen, and do not get access to a free special weapon until they hit a unit size of 15 (compared to 10 for the Grey Hunters). The one fun thing they do get is Lukas the Trickster as a 140 point upgrade (once again a huge amount of points). They do however get a cool set of abilities in Berserk Charge and Headstrong. Berserk Charge gives +2 attacks when going into close combat and have to skip the shooting phase to charge into battle if they are within 6" (unless they are joined by an HQ or Wolf Guard). So the question begs, why not use the Blood Claws? They can be used, but you have to get them to a tactical advantage. This means you need to give them a Land Raider/Redeemer/Crusader and a Wolf Guard, Wolf Guard Battle Leader, or Wolf Lord with an invulnerable save to get them close, get them into the fight, and give them an opportunity to do some major work. I mean who doesn't love 4 attacks on the charge.
Flipping through your Space Wolves codex you pass by Grey Hunters, Wolf Scouts, Long Fangs, Lone Wolves, and Wolf Guard which find their way into almost every Space Wolf Army at some time or another. Then there is the Fenrisian Wolves. They are 8 points a piece, can have anywhere from 5 to 15 models, are like Marines except they have 2 attacks, Leadership 5, and a 6+ save. You can also upgrade one Wolf to a Cyberwolf for Toughness 5, 3 Attacks, Leadership 6, and a 4+ save. They have the Counter-Attack Special rule, are beasts (12 inch move, not slowed by difficult terrain), and have Fleet and Move Through Cover. So why not use them? I would say you can use them in a couple scenarios. With Canis Wolfborn, they can become troops (although they can't score), and give you a option of a max squad of 14 wolves with 1 cyberwolf coming in at 128 points (much less than Grey Hunters or Blood Claws) and more maneuverable than most troops too. You can also throw them around a Wolf Lord on a Thunderwolf mount for an additional 15 wounds, 31 attacks hitting like Marines, and if they charge, that is an additional 15 attacks (46 attacks on a charge with re-roll if your keeping track).
It is kind of funny that in the book right after the Fenrisian Wolves are both the Skyclaw Assault Packs and the Swiftclaw Biker Packs. These guys in the fluff are just Blood Claws that were so wild and reckless that the Wolf Priest saw it fit to strap a Jump Pack to their back or set a Bike under them. Either way they rarely saw the field in the 5th edition due to the fact they are Fast Attack (which holds the Land Speeders and Thunderwolf Calvary as well), they have the same profile as a Blood Claw (except for the Bike which is T5), and they have the same special rules including Berserk Charge and Headstrong. The only way in 5th to make these guys truly effective was to take a Wolf Lord, Rune Priest, Wolf Priest, or Wolf Guard Battle Leader on a Bike or with a Jump Pack which didn't really help any of those units out.
How about now? Well let's face it, the Jump Pack and Bike have a bit of an upgrade now. The Bike now has a Jink Save of 5+ on shots or if they turbo boost they gain a 4+ save. Now combine that with the fact that they have Hammer of Wrath on the Assault and they suddenly become more viable on the battle field and at 25 points per model, I think we may have a slot for them especially considering that for 30 points we can gain an Attack Bike with 2 wounds and 2 attacks. With anywhere from 3-10 Bikers in a Pack, that is a lot of aggressive Wolves on Bikes.
The Jump Pack also allows for a couple special rules. With the Hammer of Wrath (when using Jump Packs on the Assault), re-roll on charge distance, and that these guys gain an additional attack on the charge for +2 attacks instead of +1, the Skyclaws have some serious attacks. Combine that with 18 points per model, a Skyclaw can have a Mark of the Wulfen (D6+1 attacks), and anywhere from 5-10 members in the pack, these Wolves deserve a shot at getting onto the field (possibly Deep Striking in and then Charging a back line unit).
So what do you think so far? These are just a few of the less common units on the battle field and I hope that I made the case for them so far. The Codex is only halfway done and I still have some fun units that rarely see the battlefield but I am hoping to make a case for their presence.