The reason you kick the FG first is that you're already in FG range. This is sonething that you may not be able to achieve even if you recover the onside kick. I've heard lots of commentators say "That sack takes them out of FG range". Never once have I heard of a team being out of TD range.
Couple stats for you:Brady is
52% inside the 10
60% inside the 20
64% from the 20-49
64% from midfield to own 20
Inside the 20 on 45/74 with 21 touchdowns
He throws 28% of his passes for Touchdowns inside the 20 (which he was at the 23 just outside this range)
Very cool information
http://www.advancednflstats.com/2009/11/two-minute-drill.html
You wil note on the graph its with 2:00 not :40 but your
chances go from about 56% chance of a TD on the 23 down to 34% when your on your own 40 starting out. This would be DRAMATICALLY less most likely if it were skewed to the :40 left time frame.
Also note you are about a 50% chance for a FG when starting on your own 40, again this is was 2mins remaining and this as well would go down depending on WHEN you scored the TD.
The bolded is actually rather interesting. Ignoring the time difference, with a 0.56 probably of success when going for the TD, and assuming a successful onside kick then, a 0.5 probability of successfully getting a FG (I am assuming that means not only getting into range but converting said FG), the probably of a tying the game (again taking the onside kick as a given) is 0.28.
On the flip side, also ignoring the time difference, let's say the probability of making a 40 yard field goal is 0.8 (which based on what data I could find is about right), and then again assume onside kick is converted, and a 0.34 probability of scoring a TD, the probability of tying the game is 0.272.
So, the odds are almost exactly the same no matter which order you choose. However, if that 0.5 in the first case simply implies getting in position to kick a FG, then we're looking at 0.56 probability of TD, 0.5 probability of getting into FG position, and we'll just assume 40 yard FG, so 0.8 probability of successful conversion, the probability of tying the game drops to 0.224.
I'm not sure which case is right, as I didn't look into the charts/data you linked to, but I found it interesting nonetheless how if we assume the first case to be accurate, and of course assume the data you provided to be accurate, it makes almost no difference which order is chosen (with 2 minutes remaining, anyway--my guess is that as the time remaining decreases, option 2 becomes more and more favorable.
ETA: Of course this is all rather simplistic because it fails to take into account how long it takes to score in the first case, and thus the fact that there would be less than 2 minutes remaining to get the FG, which, if nothing else, lends further credence to option 2 being the best choice, which in this case is FG and then TD.