I see what you are saying. However, I thought they proved themselves as great game designers and mediocre programmers with the first game.... which we just got more evidence of with the second game. Hopefully they get some excellent programmers and a army of graphic artists for the 3rd game. That's really all they need.
I see what you are trying to say, but don't forget they did ramp up their developer employee count for SoD2 and switched engines at the same time. They are still a smaller studio amd no where near AAA size.
regardless of their bugs, they have managed to ship 2 games that people love and both had over 2 million players and the 2nd is still growing. I would be surprised if it broke 4-5 million eventually.
Please also be careful with the "mediocre" programmers claim. Software projects are extremely complex. You can have the best programmers in the words and still deliver a buggy product if requirements are changing rapidly, management is inexperienced with large teams, poor project planning, your top people had to spend most of their time training new hires, hit the mythical man month, etc...
It's way too easy for people to blame programmers for failures when there are many potential root causes. Note: I have run software projects ranging 3 people to over 600 people in size. My historic job has been to find and fix the issues that cause these sorts of problems and it is extremely challenging to do.