None are really the most important, without looking at them combined you sort of lose the context. Of the three ZR is probably has the strongest tie actual performance but using it as a basis for judgement is pretty weak.
If I were to go with 1 defensive statistic as the most telling I would probably use Fielding Runs Above Replacement. Damon was about 14 RAR
in 2005, again one of the lowest scores in his career.