The field of organizational behavior has exploded in recent years, particularly in relation to organizational accidents such as airplane crashes.  It is rare when a major catastrophic event can be attributed directly to one cause.  In most cases, the person who is the last line of defense commits some sort of blunder to contribute to the mess, but there is still usually a long line of contributing factors that all had to line up in order for the final error to be made.  A good organization will have fewer of these latent conditions that allow people to make mistakes, but they will still exist as long as humans are involved.  This article examines turnovers in ultimate with an eye towards improving the organization/team.

Let me state first that this is not intended to absolve the prime culprit of responsibility, or to point fingers at any level.  Rather, I would like the secondary contributors to realize that just because they didn't throw it away or get scored on, doesn't mean that they were mistake-free.  Players can usually get away with small mistakes because bad teams are unable to capitalize on them.  Good teams and good players will take advantage, though.

Types of errors:

1. 100% individual errors
This would be dropping a perfect pass, or turfing an easy forehand.  These are often concentration errors, or just random blips that you would have no reason to expect should happen again.  As the overall basic skill level of a player or team increase, the number of these errors should decrease.  Repetitive practice can help eliminate or at least reduce these, so as long as these errors constitute a large portion of your team's mistakes, you ought to be spending a significant portion of your practice time on the fundamentals.  Conversely, if drops comprise only 5% of your turnovers, then you are probably wasting your time on catching drills.

2. Acceptable errors based on reasonable decisions.
In a 1972 case, the US Supreme Court declared "Safe is not the equivalent of risk-free." A "safe" investment in a low-interest savings account is a bad long-term investment compared to the more volatile stock market. I've written before about the risk-reward curve and how it applies to ultimate.  The accompanying figure shows such a curve.  A 90% pass can be better than a 98% pass (or even a 50% pass vs a 100% pass) if the team stands to gain a lot from it.  There is an acceptable level of risk associated with most passes, with this risk depending on the game situation, the skill of the thrower and receiver, the inherent risk of the pass, and how that pass fits within the guidelines of what we call "good choices."

2a. Unacceptable errors based on unreasonable decisions
These are passes that carry too much risk for what they accomplish.  Hucks into triple coverage, certain "art" passes which don't get you much, big crossfield passes if you don't have that throw, and the like are generally the worst turnovers, the ones that draw the most ire from your teammates, and the least excusable, even when they work.  From time to time, we all might engage in this behavior as a way to test ourselves or to expand our envelope or to practice difficult plays, but it becomes less and less acceptable to do this as the season progresses.

3. Communication errors
These have to reduce as the season goes along.  When it happens, discuss it after the point, don't blame.  Learn from it.  Go this way when I wanted you to go that way once, shame on you.  Go this way when I wanted you to go that way twice, shame on you.

4. "What's wrong with right here?" errors
In one perhaps apocryphal story, Kenny Dobyns was wide open for an easy goal, but the pass came in well behind him, and he couldn't hang on to it.  "What's wrong with right here?" he screamed, holding his hands directly in front of his chest.
Most drops fall into this category.  It's still the receiver's duty to catch it, but the thrower must realize that any adjustment the receiver has to make increases the odds of an incompletion.  If a lot of your passes are dropped, it is probably due to your throws being tough to catch.
A less obvious member of this category is when a receiver cuts to a less-than-perfect spot.  Just like above, it's still the thrower's responsibility to make the pass (or to avoid throwing it), but the receiver should do everything in his power to make the thrower's job as easy as possible.  In a practice this fall, a teammate had the disc about 10 yards from the end zone and 5 yards from the forehand sideline and was being forced middle, I began my cut from about 15-20 yards outside of the end zone and 25 yards from that sideline.  I ran inside my defender and broke to the cone.  The thrower saw the beginning of my cut and so threw the disc to a spot well into the end zone, expecting me to flare more.  What I should have done was to take a different angle on my cut that would have given him more margin on the throw and that would have allowed me to adjust to a greater variety of throws.  Instead, my path dictated one particular throw, and when it didn't come, I couldn't chase it down.  The thrower still has the primary responsibility, but I could have made his job a lot easier without making it much more difficult on myself.

5. Team errors (three or more players share responsibility)
6. Systemic errors (imperfect strategy)
These can have a lot of causes and may generally be referred to as "stall 9 errors."  Sometimes these are simply the result of good defense, but more often they involve subtle errors by cutters and potential cutters, combined with less than perfect ability by the thrower.  One way to reduce these is through on-field communication by players.  In decreasing order of goodness, the team can:
a. Call a play specifically designed for that exact situation,
b. Call a play appropriate to the general situation but perhaps not the best play,
c. Stop the flow but take steps to reset the offense into a more basic configuration,
d. Improvise a play call (for example, "Hey you, cut to the cone!"),
e. Rely on its normal rules for offense, or
f. When the cutters do nothing because of a lack of a call, the thrower calls timeout or forces up a bad pass on stall 9.

If it gets down to the final option above, there will be many contributing factors besides just that "he threw it away.".  The first cutter goes deep but is double-teamed.  The receiver poached off of hesitates in coming in.  When he does come in, he takes a non-optimal line and is picked up.  The thrower focuses on these guys until 6 before looking for a dump.  The closest handler hesitates for a second before starting his cut.  The second handler would be open for a dump, but doesn't tell the first handler to clear.  The other two guys in the stack just stand there, allowing one man to poach in and stop that lane while the other defender can cover both.  Meanwhile, the first handler cuts for the dump but is shut down, and the second handler makes a last second cut to the line, is blanketed by the defender, and the pass goes by both of them.  A situation like this is partly due to systemic error, in that the strategies are not perfect and can not conceivably cover all contingencies, and partly a team error due to the collective errors or imperfections of the players on the field.

The well-prepared player will have thought about these situations and rehearsed them in his mind many times before they actually occur on the field.  You may work out your body so that execution errors are minimized, but you also have to work your head so that mental errors are also minimized.  If any of the above players recognized the situation a split-second earlier, the turnover could have been avoided.

The team also has the responsibility to create a system where these errors are less likely to happen.  Plays need to have backup plans if they don't work, and standard offensive schemes need to have ways to reset.  Furthermore, the team needs to consider its skill level in crafting strategies, so as not to require throws or cuts that are beyond the ability of most of the players.  Lastly, the system needs to be flexible enough to allow players to exercise judgment.  No rule can perfectly apply to all situations, so blind adherence to what should really be just guidelines will sometimes contribute to turnovers.  If players are not given the opportunity to learn to think for themselves, they will not be able to handle unexpected situations.
A good team will consider the "human factors" I have described above in forming their strategies.  A bad team will have an organizational culture of blame instead, and will believe that all their problems are the individuals' faults and can be eliminated through trying harder or by running one more drill.  Be a good team.