4 lands with a 2- or 3-drop is almost always a keeper to me. I unfortunately can't say more due to not knowing what exactly were the remaining 2 cards in your hand.
Speaking of keep or mull, here's an intersting one:
You're playing Orzhov splashing Blue off one Azorius Guildgate, one Gateway Plaza and one Azorius Locket.
You're on the play against an unknown opponent with this hand:
Orzhov Guildgate,
Plains,
Mortify,
Lawmage's Binding,
Syndicate Messenger,
Undercity Scavenger,
Grasping Thrull.
Keep or mull?
Keep you got good mana, removal, creatures and some lifegain... if things go sour.
If the deck has 4-6 2 drops then is a slam keep.
I would definitively keep it.
---
On other news... I think I'm starting to get a better grasp of this format, Gruul has been performing solid with 5-6 wins per run but Orzhov is finally coming together more consistently.
I think I'm starting to find some interesting interactions that are allowing me to have some edge in stall boards... I'm also going into a more aggro approach in the early game and adding small deck building concessions for little interactions like the Footlight -Bladebrand combo
I build a very cool Gruul deck the other day that went 6-3 but it was amazing to play... it had some Savage smash a couple of big fatties and like 4 Sauroform Hybrid... that guys has come out rather late and even wheels, which I find nuts coz that is one amazing 2 drop! Bots are mad!
Anyway apart from the Gruul deck I also had 4 goblins gatherings 1 team pump spell, 4 gates, one Ram, one Colossus and one gate ablaze.... the deck was all over the place but man that thing was so fun to play... so many angles for attack... It was a shame I could not take it to the 7 wins.
Another 7 wins deck
This one does not look like much but has some cards that have really over performed... but this time I started with a miserable 1-2 but then I made some swaps to add a little early game and BAM! 7-2
Funny thing is that 2-3 games were won by early aggression with the stinky 3/1... I think people are durdling around too much and a fast start can provide some free wins here and there...
I think Gruul is very good for that but needs to grab 2 drops and tricks, pressure your opponent to trade down and then close games with those 4-5 cmc fatties... but the deck needs early aggression in order to work well.
In Orzvhov this cards have over performed for me:
I also add quite often one Debtors transport and feel quite happy about it... this thing demands an answer and then you are getting 2 fliers in the exchange... pretty solid IMO
this format is FUUUN!