These are the tough questions that I was looking for.
If you look at just the robot performance, I don't think we made any real improvement from previous years. Last year we had a workable drivetrain, an anemic frisbee shooter, and a sad floor pickup. This year we had a workable drivetrain, a mediocre ball pickup, and an often-broken ball shooter.
Some of the project engineering changes we made this year were beneficial: our actions during the early build season loosely resembled the engineering design process. We didn't start robot design until we had a game strategy, and we didn't start fabrication until we had a design. We allowed ourselves to "close the loop," returning to the strategy and design steps on occasions when it felt warranted. Every machined part existed in a working CAD model before it existed in real life.
Although we made those incremental improvements, we still didn't prototype nearly enough (I don't know where we would have found the time!) and I don't think our strategy decisions were entirely based on a realistic understanding of the game dynamics (not sure how to solve this one either). We're also at serious risk of backsliding towards our previous behavior.
I believe the single biggest reason for our poor performance was lack of practice. Our total practice time measured in the single-digit hours.
I think I would totally use this system again in an FRC game, even if it turns out to be inherently flawed. I think this probably means that I'm never going to get a blue banner :/
If I used it again, I'd make a few changes. At the top of my wishlist would be (1) better access for repairs, (2) better wheel retention, (3) a chassis design that doesn't rely on the gearbox frame for internal support, and maybe (4) some
follower wheels for additional position-based sensor feedback.
Of these questions, this one is the easiest to answer: There were no reasons for these decisions. All our team had was a weak desire to conserve weight and zero understanding of the physics of electric motors. We didn't follow anything resembling the engineering design process, and we certainly didn't do any math before building a robot subsystem.
My primary goal for the 2014 season was to be a better mentor to the students who want to pursue engineering. Working towards the engineering design process, justifying design choices with analysis, and breaking down unjustified beliefs that don't stand up to rigor were the major areas where I spent most of my energy this year. I feel like I was only partially successful and have a lot to learn.