Looking over the various categories, how is FDR only fifth for economic management? None of the presidents ahead of him dealt with anything nearly as complex or challenging as he did; not only the greatest economic crisis in American history, but also converting the whole economy onto war footing.
His approach to economic management was to basically try everything and see what worked. It basically was a slap-dash approach that resulted in successes and failures that really didn't get us out of the Depression, but his economic reforms did end up putting us on a sound footing afterwards.
An example of one of his failures is that he thought balancing the budget might work in 37 after doing a bit of deficit spending in 33-34s. Well, it didn't work and put us back deeper in the depression until we stopped doing that.
Also, I'd imagine that there are probably a few historians who are free-market religious zealots who believe that everything would have been solved if the market was simply left to its own devices and ranked FDR extremely poorly as a result.