These sliders are based mostly on the excellent research Matt poured into his slider experiments. I, again, want to advance a house rule for Career Mode if your skills are not quite up to scratch or you want to enjoy a bit of homefield advantage "realism". Use Professional difficulty for HOME fixtures, use World Class for AWAY fixtures, or some variation on that theme. It makes the game pretty rich. For neutral fixtures, e.g. cup finals, use the harder difficulty.
Professional is now a fairly excellent alternative to World Class, but I still recommend World Class as the default. Legendary is silly and filled with cheating CPU gimmickry, but I digress.
One final note: Another reason for my posting these sliders is based on the 10 minute halves limitation. I played 15 minute halves last year and found it equal parts immersive and exhausting. I don't have the time or patience this year for that. Hence, my decision to use Matt's sliders as a foundation, with a few tweaks to open the game up a bit and compensate for my not-quite-ninja skills. I don't use finishing moves / street fighter combos when I play. I believe in a SIM experience, but I want to enjoy that experience 20 minutes at a time. Because of the 10 minute halves length, you'll typically see around 14-20 combined shots on goal and lower goal totals. I'd be surprised if there are more than 2.5 goals per game with these sliders. I defend well enough and attack poorly enough to get that average anyway. Hah!
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UPDATE | October 31, 2014: I highly/intensely/categorically recommend that you use Fidel's gameplay mod. How does it work? Easy, you download a tiny text file, called cl.ini - then simply copy and paste it into your FIFA 15 directory. There are many things that Fidel addressed with his mod, but primarily he addresses the insane CPU pressure/tackling while improving significantly the ability for humans and human AI to defend. It's truly essential. Because I use this mod, I cannot speak for how my sliders will play without them.
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v1.1
Controls: Full Manual
Difficulty: World Class (or Professional for home fixtures)
Halves: 10 Minutes
Speed: Slow
Human/CPU
Sprint: 42/42
Acceleration: 50/50
Shot Error: 52/55
Pass Error: 53/68
Shot Speed: 48/48
Pass Speed: 50/50
GK Ability: 45/40
Marking: 50/45
Run Frequency: 40/25
Line Height: 58/58
Line Length: 42/42
Line Width: 38/38
Fullbacks: 60/60
First Touch Control: 60/75
Previous Versions: