I'm going to piggy back on this post. I don't know what it is, but I have never seen the number of trades that folks report seeing. I play with weekly prep off and preseason off, and I average maybe 2/3 trades a year and usually it involves non-starters (the biggest name I have EVER seen traded in two years with the game is Michael Strahan to the Vikings).
I did see some poor roster management during one franchise I was doing in that the CPU was releasing players who were hurt. That was also a franchise that I was using weekly prep with and I think that may cause a lot of problems. Every other franchise I have ever done I see the CPU make smart roster decisions (they use the IR, trades are minimal and make sense, and the FA stuff is actually not bad). I also have injuries at 30 and have never had them below 22 in any of my franchises.
Like I said, I guess I have been lucky, but I just don't see the trades people talk about. On another note, I did see something cool in Free Agency. There was a player on my team who came up for free agency. I made my offer, but ended up being the 3rd best offer overall. To my suprise, the player chose to sign with me. The only thing I could think of was that he wanted to come back to my team. Makes me wonder if they have programmed that kind of logic in there, or it was just a one time glitch.