[obaslg]

1) 4-man rotation: I use it exclusively. The SP goes fewer innings per start, but many more IP total over the year. I don't know where it is, but somewhere there's a chart of how many pitches a SP can pitch every 5 days - that is, if he's pitched at all in the preceding 5 days he can't go quite as long. I haven't seen any performance difference - I haven't done any scientific tests, but I've had some stupendous seasons with SP in a 4-man (e.g., two 30-winners in one season).

I play in a very competitive division in my online league, so on that basis it's a no-brainer. It might be different if I was in first with a big cushion, and wanted to give a youngster some experience.

Some think that it makes injury more likely. I don't trust anything anecdotal regarding injuries, since the N is so small, and I've never done a real test.

Be warned that one of the few differences between a "MR" with starter endurance and a "SP" is that the "MR" will not be able to pitch on only 3 days rest, so if you plan to put that kind of guy in a 4-man rotation, make sure to change him to a "SP" at the start of the season.

An advantage of the 5-man rotation is that if you have an injury you can just temporarily go 4-man.

2) In your situation, unless your #5 was pretty close to as good as your #1, I'd do a 4-man, and trade away anything extra, though as I said, if you're not competing this year, you might try to get as many guys into the rotation as possible for the development experience.

3) I haven't played SP at MR too much. One thing for sure: they will complain, and I assume that means they will not perform as well - I haven't heard of any test of that. The endurance seems fine, though.

4) GB/FB can be very important. I had Hampton (70% GB) and an A/A middle infield. His ratings started to tank, especially in walks (like 2-3), but he still did fine. I played out some test games and watched his bizarre strategy: walk, DP, groundout; repeat. He had a 2.95 ERA with 130 walks.