At last, I have found evidence that pessimists have an integral role to play in a high performing team!!
My interest in this is due to being a Pessimist. I actually prefer to be seen as a Realist but society unfortunately sees me and other Pessimists differently!!
It is great to be surrounded by Optimists but the reality for me has been the avoidance of bad things that we know are likely to happen but don't want to acknowledge them because being Pessimistic is not viewed well. I have been in so many situations during my career when I have seen failure approaching and if accepted it can be avoided with a Plan B, however, the Optimists refuse to admit the impending doom and prefer to deal with it when it arrives. The situation is then more harmful and takes longer to turn around.
The article proves to me that high performing teams need a sprinkle of everything as if they cannot sustain success if they all have the same view on life and input into the team.
Now that I've convinced you that a pessimist can be a valuable part of your team, you need to remember that they should be managed differently than your optimists. As a leader you need to ensure that pessimists be heard and their opinions valued, yet an opinion or concern should only be stated once. Rehashing the same concerns over and over is a waste of time and energy for everyone and decreases productivity. Remember the story of Bob Ebeling. When a pessimist voices his concern don't be dismissive but facilitate a discussion about his concerns with your team. Gain insight from other team members of what they think about the pessimist's issue. If the team believes that the concern is manageable then the concern should not be discussed again.