Interview skills are not the same as work skills. This cannot be said often enough. Based on my own unscientific observations, the most common error that hiring entities make is to place way too high a premium on a candidate's demonstrated enthusiasm to get the job...and not enough emphasis on that person's motivation to actually do the job.
Think dating and marriage -- two completely different sets of competencies, right? You could launch a convincing argument that the best characteristics of each are incompatible -- mutually exclusive, even -- with the other. That person who was sooooo exciting to be with, who swept you off your feet in a whirlwind of Hollywood-style romance, never once letting you catch your breath...can you see him taking out the garbage or helping with the dishes? Probably not. Likewise the stable, loyal, nurturing and empathic life partner with a sturdy sense of responsibility is very possibly the most boring date in the world. (She'll always be there for you, though. Chicken soup, anyone?)
Preparing, rehearsing and polishing one's interview material Â-- on top of having done the necessary research -- generally result in a strong audition. But unless you're interviewing for a position as a full-time interviewee, these talents have little or nothing to do with the role for which you're being hired. Being an extrovert is super-helpful in winning the votes of confidence you need to get the offer. It may not provide any miracles, though, when it comes time for your performance review.
On the rare occurrence when we've talked to a prospective client and the client ultimately decides to hire another search firm (it happens), we like to follow up in a couple of months and see how their search is progressing. What we usually discover is that the other firm was much better than us when it came to marketing themselves...but not so impressive when it came to execution. We pick up a fair amount of business that way, on the rebound from competitors who are all talk and very little walk.
So if you were runner-up for a position you know was right in your sweet spot, what do you have to lose by calling the hiring manager back ninety days later and asking how that new hotshot is working out? You may be surprised to learn that she wishes she had gone with you, the boring date who doesn't mind changing an occasional diaper. Or something like that.
Just a suggestion. Because you never know what might happen.