So, I think I'm likely the person that scours this data more than just about anyone. I can think of 1-2 others that might be as maniacal about is as me... but regardless I watch it pretty closely. I have a few numbers that I personally care about more than any others as I'm evaluating the overall financial success of the project for people staking cards.
The first number I watch is the marketcap. We have 79 cards in the game that are available as alpha, beta, or promotional editions. If you total up the last card price that the card sold at, multiply by the number of those types of cards in existence, lastly sum them all together, and you get what we're calling the Monster Market Cap. You don't have to do any math. The bot that 
To put our current position in perspective I like to visit coinmarketcap. As you can see if we were a standard coin we would be in position 845 right now.
This would put us in the top 40% of all coins that exist. We have a ways to go for sure, but that's not bad considering we've been here since May.
People are the Value
The number 1 thing in my eyes to watch is the number of people playing the game. 
As you can see we just crossed the 2000 player mark. That's a different number than the number of people with accounts. We have just under 3k accounts now who have purchased the starter pack, but only 2000 of them are playing, which means the other 1000 either don't take it seriously at all, or really only view this as an investment rather than a playable thing.
Matt had some ethereum game devs bragging to him about how many people were playing their game. They were near the most played game. They had 12 people. By grand theft auto standards Steem Monsters is still nothing. Not even a spec. By crypto it's the biggest game going by number of daily players as far as I know.
Actual value of muh cards
Lastly I like to track how much my personal holdings are worth
No, I haven't spent $70k buying cards, but I have seen my investment steadily going up. I see new players, a higher marketcap, passionate fans, tournaments haven't been put in place, we crossed 350k games played, and marketing efforts haven't kicked into gear yet and won't until tournaments are here. I think this game has a ton of potential and even just where we are at it's already showing a good time and great great returns. This is why I have $74k in the cards already and plan on buying more.
Card delegation will be a thing. I see investors renting cards to players who are going after tournament rewards and the investors will get steady passive rewards from doing it. It's gonna be a beautiful thing for HODLers.
Anyway, this isn't financial advice, do your own due diligence, it's for entertainment and information purposes only, I don't know you or your finanicial situation well enough to give the advice that you should SODL HOUSE AND HOLD MONSTERS, and even if I did give that advice you'd have to vet it through your own process and be responsible for your own decisions.
I'm happy with the returns I'm getting. I think they are some of the best in crypto. If I give any advice it's that this game, community, and opportunity are worth investigating.