Looking at the clan abilities, there seems to be a discrepancy between what is supposed to be the central color of the clan and what are the important cards.
Lets take a quick look at the clans in Khans and the key cards in constructed those abilities were on.
Abzan: Outlast isn’t really a player in constructed. I did see a couple of [scryfall]Ainok Bond-Kin[/scryfall]s and I’ve been trying to make [scryfall]Abzan Falconer[/scryfall], [scryfall]Herald of Anafenza[/scryfall] and [scryfall]Tuskguard Captain[/scryfall] work, but haven’t been able to. Anyhow, if these are the key cards, Outlast is rightly and strongly centered on white.
Jeskai: As blue is a pretty pure control color, Prowess, a creature ability, is not going to be important to them. Sure, [scryfall]Pearl Lake Ancient[/scryfall] has it, but its not the reason you play it. I would have hoped cards like [scryfall]Jeskai Sage[/scryfall] and [scryfall]Jeskai Elder[/scryfall] could see some play, but wasn’t exactly holding my breath. The most commonly seen ones are [scryfall]Monastery Swiftspear[/scryfall] and [scryfall]Seeker of the Way[/scryfall]. So, the key cards are in color other the central color.
Sultai: Black and graveyard go nicely together, so its a pity they cards are in the color with the least graveyard interaction, blue. [scryfall]Treasure Cruise[/scryfall] and [scryfall]Dig Through Time[/scryfall] have had a huge impact on all constructed formats, even up to Vintage. Sure, black has [scryfall]Murderous Cut[/scryfall] (and received a couple of good cards in Fate, but I’m discounting those for the sake of simplicity and fairness between colors), and green has [scryfall]Become Immense[/scryfall], but neither of those could ever have the same impact, as even though they are strong cards, they are fairly replaceable.
Mardu: The major card with Raid is [scryfall]Wingmate Roc[/scryfall], which is White. Then there’s the cards I love to play with, namely [scryfall]Bloodsoaked Champion[/scryfall]. Sure, red has [scryfall]War-Name Aspirant[/scryfall], but that has since been outclassed and it never was that good to begin with. Maybe [scryfall]Howl of the Horde[/scryfall] could have had some impact, but never did.
Temur: Ferocious seems to be the ability that has most cards in Standard, but that’s actually pretty weird. Many of these aren’t in decks because of the Ferocious, although it can bring extra benefits. There are some cards that are played for the ferocious benefit ([scryfall]Crater’s Claws[/scryfall], [scryfall]Flamewake Phoenix[/scryfall], [scryfall]Stubborn Denial[/scryfall]), in others its not that important ([scryfall]Wild Slash[/scryfall], [scryfall]Temur Battle Rage[/scryfall], [scryfall]Heir of the Wilds[/scryfall]). Other cards have seen some play as well ([scryfall]Feed the Clan[/scryfall], [scryfall]See the Unwritten[/scryfall], which I think is being set up for Battle for Zendikar, [scryfall]Shaman of the Great Hunt[/scryfall], [scryfall]Savage Punch[/scryfall] and we were planning on putting [scryfall]Road of Challenge[/scryfall] into a GW Aggro deck for GP Krakow, but didn’t end up playing that deck). Again, this is supposed to be a green ability, but seems to be much more in red.
Of course, we need to look a bit deeper to see the whole picture. Forgetting white, blue has card draw to keep the prowess going, black has discard and self-mill to use with delve, red likes to attack and green has the biggest creatures so that your ferocious is more effective with them.
Moving into Dragons..
Dromoka: Bolster hasn’t had much of an impact either. Actually, none in Dragons. Only a little bit in Fate ([scryfall]Abzan Advantage[/scryfall], but that’s in the past, as now there’s a better option ([scryfall]Dromoka’s Command[/scryfall]). [scryfall]Anafenza, Kin-Tree Spirit[/scryfall] might be a player somewhere in the future, but not right now.
Ojutai: [scryfall]Narset Trancendant[/scryfall] is pretty nice, although not as good as many people first thought. However, it doesn’t really count here. I could see [scryfall]Center Soul[/scryfall] or [scryfall]Artful Maneuver[/scryfall] get some play, but probably not much. Again, not blue…
Silumgar: The only Exploit one that’s seeing play right now, is [scryfall]Sidisi, Undead Vizier[/scryfall], but I could see [scryfall]Profaner of the Dead[/scryfall] and [scryfall]Silumgar Sorcerer[/scryfall] see some play in the future. Maybe even [scryfall]Minister of Pain[/scryfall] could have a role.
Kolaghan: The marquee Dash card is [scryfall]Zurgo Bellstriker[/scryfall], which is quite strong. So is [scryfall]Lightning Berserker[/scryfall]. I personally like [scryfall]Pitiless Horde[/scryfall], but it isn’t a very big deal. A win for red here.
Atarka [scryfall]Surrak, the Hunt Caller[/scryfall] is the only Formidable creature here worth mentioning, even if I wanted to mentino Levy’s Big(ish) Red from the Pro Tour, which played [scryfall]Dragon Whisperer[/scryfall]. A sort of win for the green.
All in all, Dragons seems to have focused on the central colors better. In Khans only Temur sort of got it right, while in Dragons of the broods had it sort of right. Of course, these cards will still be in Standard for a while, so perhaps someone will break one or more of them.