In general, I agree with a lot of your points, but it's important to remember that strongest/weakest depend on different league features and what we mean by those terms. Here are a couple different things to think about:
Here's how the different positions rank in terms of their median Yahoo 5x5 rank. I did this for mixed, 12 team, 14 team and 16 team leagues. In this case, the rank order was identical for 12, 14, and 16 team leagues. For OF, I assumed 3 OFs had to be played. The number in parentheses is the rank of the median player at that position:
12 team: 1b (32), SS (58), 3b (76), OF (79), 2b (108), C(238)
14 team: 1b (41), SS (68), 3b (78), OF (96), 2b (114), C (249)
Notice that in a 14 team OF and 3B are pretty close, while in a 14 team the gap widens. Solid mid-range players at 3B, where more of a dropoff in OF
16 team: 1b (58), SS (78), 3b (87), OF (116), 2b (131), C (280)
Another way to look at position strenght is at the peak performers. Here's how the positions rank according to the top 3 players (9 for OF) at that position. Numbers in () are the average rank of the top 3 guys. This is the same for all 3 leagues:
1b (4), OF (12), SS (13), 3b (20), 2b (32), C (127).
So, OF jumps from looking to be barely above 2b to being the second highest rated position. That seems to say to me that there's some really important separation between the elite OF and the average OF. So, downgrading its priority based on its average production might be a mistake.
Finally, another way to look at it would be how bad is the bottom. To look at this I looked at the average rank of the bottom 3 players at a position. This differs for each league because you are looking further down the list for the bigger leagues. So, here's how the positions rank in terms of what is basically an indication of their replacement level player. Number in () is the average for the bottom 3 guys:
12 team: 1b (92), 3b (102), SS (114), OF (159), 2b (166), C (298)
14 team: 1b (110), 3b (131), SS (141), OF (188), 2b (191), C (341)
16 team: 1b (125), 3b (150), SS (159), 2b (208), OF (209), C (366)
The depth at 3B and the drop-off in the bottom tier SS and OF is what stands out here.