Roddick isn't really that much of a hit and miss player like you describe. The likelihood is something in the middle turns up and Kohlschrieber loses in 3 or 4 sets but not without causing a little trouble. Neither of the options you give are likely at all.To answer the question, it's easy: if the real Andy Roddick (the one with the one dimensional but very effective flat, power hitter) shows up, Kohl goes home in straights.
If this moonballing passive mug who skipped through his first two matches against club players shows up, upset alert, Kohlschreiber wins.
Probably.Roddick in 5 sets, Kohli will choke if he sees himself close to crossing the finish line