The only other realistic option for the designated penalty taker is Smeltz, who has a history of missing them in high pressure situations (see: NZ vs Honduras, penalty missed in 90th minute) [/quote]
That was a friendly. Pretty much the opposite of high pressure.
That makes it even worse, doesn't it?
Historically it appears that defenders make good penalty takers (OK, I do not have a reference ready to support it) as they are less likely to engage in risky "mind games". They often have just one way of scoring (low, hard shot near the post), but do it reliably every time.
Italian Serie A defenders of years gone by come to mind, as do many Bundesliga ones.
You could argue that strikers are naturally "wired" differently from the centrebacks. I recall a number of high-pressure settings where the striker was the one that scuffed the penalty. Think of Mark Viduka against Uruguay in Sydney in 2005 second leg (he shot over the bar).
In contrast, Alessandro Del Piero is so relaxed at this stage of his career (he is 39) he hasn't missed any in A-League that I know of (but correct me if I am wrong).
Del Piero (from one of the links below): "The Italian legend had a fantastic penalty record for Juventus and the Italian national team, but he has blotted his record somewhat by missing two of his five penalties last season for Sydney FC. This leaves him with a career record of 61 from 65 attempts, a conversion rate of 94%."
Top 15 world-wide based on stats: http://bleacherreport.com/articles/1324429-ranking-the-15-best-penalty-takers-in-world-football
Top ten in top five UEFA leagues: http://talksport.com/football/european-footballs-penalty-kings-revealed-130911596
Good top ten list: http://www.thesubsbench.ca/top-ten-penalty-takers/
Here's the Daily Mail's list of the top 50 in world football ( starts with positions 10-1 and has links to the other positions in lots of ten):