A very, very common situation for me is this - I work out, I rest, I come back weaker. A number of books/people have given reasons for this:

1. Not enough sleep.
2. Not enough protein.
3. Frequency too high.

Etc. Can we get a comprehensive list of the factors (both behavioral and genetic)? Also, I would like to know what happens when a muscle can't repair itself over the short term. What happens in the long term? 

Edit: I am really interested in the question overall, specifically in terms of what genetic potential is. Btw, I have read Supertraining (years ago), so I am familiar with the graph in the comments. 

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Anyway, my particular situation looks like this:

\*7-8 hours of sleep weekdays, work ALL day in front of computer - 10-12 hrs  

\*Workouts look like AxxBxxA  

\*I walk a couple of miles on off-days and do hollow body holds / hip flexor stretches and some grip work, but it's light

A:
3 mile run @ 9min/mile  

3 x 17 push ups (full ROM/control)  

3 x 17 hanging leg raises  

5 x 5 bench @ 185 lbs  

5 x 5 row @ 135 lbs  

3 x 20 bw squats 

B
3 mile run @ 9min/mile  

Bunch of core stuff - supermans, planks, etc  

Calf raises, reverse calf raises (3 x 40 bw)  

Quad/Ham machine 3x8 @ light weight  

OHP 5 x 5 @ 125  

PU 5 x 7 @ bw (200 lbs) 

I have been working out for far over decade (in my mid 20s). I have been lifting seriously for maybe 2 years. My bench was 5 x 5 at 225 lbs earlier this year. I didn't stop, I didn't change anything, I just keep getting weaker. I eat adequately. 

Edit 2: Reading my own post I would be tempted to reply "Check if you are sick" - but the bench number is the only one that's dropping. OHP went up in the past few months, for example. This is also not the first time this happened. I have had a few more experiences like this with things like deadlift, where I progress, progress, and then suddenly numbers start dropping with no apparent cause (Happened around 5x5 @ 3.5 plate on DL). Btw, squat and DL aren't in the program due to muscle imbalance that I am fixing atm.