What we did
Then, like so many of our previous attempts, with a good three quarters of the clues solved, the extraction method eluded us to the end. I tried any number of arbitrary extractions: alphabetizing, sorting by total number of letters, sorting by number of overlapped letters, looking for overlaps between the different clues, and nothing worked.
What we should have done
Then, I was apparently intended to list all the "extra" letters to get the string "fastballscratcher". To quote the solution directly to prove I am not making this up:
Fastball = pitch and scratcher = itcher, so the answer is PITCHER.
Sure it is.
Would we ever have figured it out?
I'm pretty sure there's no way. Getting the more obscure clues from the pictures like "oblong" and "rear guard" would have been tough enough, but having to see the "near overlap" pattern to piece together the actual solution seemed nearly impossible. And, even if that had somehow occurred to us, I'm incredibly skeptical that "fastballscratcher" ever would have led to "pitcher".
What can this puzzle teach about good design?
Puzzles need to be as internally consistent as possible. In an environment where the minutest of details--a few digits here, an alphabetical string there--can be a clue to solving the puzzle, the number of "extraneous" patterns needs to be kept to a minimum. Two minor breaks in pattern made this puzzle much more difficult to solve, perhaps entirely accidentally.
The first and less egregious was the varying number of letters in each overlap. We figured out this might be the case, but it took a few correct identifications--we got "metropical" and "cableach" early on, and that temporarily convinced us that each overlap was exactly three letters. "Pessimisty" was enough to convince us that the overlap could vary, but we did doubt our answer for a minute or two because of a pattern we thought we had identified.
Second, and worse, is the seemingly arbitrary nature of the "near-overlaps". Not only is that a pattern I never would have thought to look for, but the position of the "extra" letter varied among the second, third, and fourth letters of the overlap. And while most of the clues contained exactly one extra letter, some of the clues had two and some had zero.
Again, it's unclear whether these extra bits of difficulty were intentional--or if a more experienced puzzler would have been slowed down at all by them. Ultimately, though, the point of the puzzle, and its most interesting part, is deciphering the relationship among the pictures and mashup phrases, not out-thinking yourself in plotting patterns within patterns.