It was only a month ago that President Obama announced the death of America’s biggest villain and proudly proclaimed victory in the name of justice.

For most, the events that unfolded and the success of the mission were symbols of American power. But to those of us who have a passion for leadership, the more subtle story revolved around President Obama and the potential impact this success would have on perceptions of his effectiveness as a leader.

April 24, just days before he announced Bin Laden’s death, Real Clear Politics, a site that averages political polls, showed President Obama’s job approval ratings at just 45%, with 50% disapproving. Experts owed those negative poll numbers to public dissatisfaction with the economy – high gas prices, debt, and signs of inflation. Less than a month later, those perceptions had changed for the better.

The ultimate measure of senior executive selection and succession planning is how well we can identify future high performers. Even with decades of research and industry leading tools, the best we can predict is somewhere around 30% to 40% of leadership potential, and this is better than most of our competitors.

So what's going on with the other 60% to 70%? The following factors are just some of the complexities of executive performance:

Success often relies on a few key decisions.
The base rate of those critical decisions is low, making them difficult to reliably measure. How many times does a leader have the opportunity to take out Public Enemy No.1 and change his/her foreign policy reputation overnight? If you are Google, is it a good choice to buy You Tube? Skype if you are Microsoft? How much do you invest in your new product, the iPod? It only takes one decision to make or break a reputation, or a company's value.

Real impact is only visible in the long-term.
It can take years before the value of some executive decisions can be measured. Experts argue decisions made more than 40 years ago to provide covert assistance to Afghan rebels’ fight against the USSR – hailed as a US victory in the Cold War – lead to the creation of modern-day Al-Qaeda. Short-term brilliance can actually have very bad effects, and, likewise, your "dud" of a leader may just have a long-term plan in mind.

Success often means having good timing.
The US economy recently took a plunge unlike anything we could have expected. Sure, there were some leaders who were responsible for the decline (yes, I'm looking at you, Wall Street), and there were policy decisions in Washington that were equally critical (Barney Frank). There were also executives who had no control over the market’s movement. If you would have measured executive performance using a “snapshot” method during that time, you would have seen some ugly metrics: sinking revenue, poor profits, negative stock value, and low employee engagement. Now, as companies rebound, those in power reap the benefits of economic recovery without necessarily doing anything.

Success sometimes comes down to luck.
Social scientists are trained early and often on the importance of statistical significance – identifying relationships that are not due to chance alone. And whatever you call it – luck, chance, or good fortune – there is an element to executive performance which is not entirely within a leader's control. President Bush took a big hit to his reputation as an effective leader due to his response to Hurricane Katrina, even though so much of what happened – an intense hurricane hitting exactly where it did – was beyond his control.

Politics makes leadership a visible sport, but it is easy to forget some of the lessons it teaches us about measuring executive performance. You may be able to identify who has the right stuff, but judging whether someone will be truly successful is no easy task.

Finally, ask yourself about your own leaders: Do they really make good decisions? Or are they riding the coat tails of someone else's decisions, reaping the benefits of good timing, and enjoying a little luck?