It is broken, but there is a workaround. I have played two games since finding out about the workaround and the pitchers are now throwing about 60% of their pitches as strikes (this includes foul balls) and there have been a handful of walks from both teams.
The workaround to MoM play is to press the "Start" button twice in fairly rapid succession prior to every pitch. It is a pain in the rear end, but until this bug is patched and if you want to play MoM in MLB 14 you are just going to have to bite the bullet and do it. By the way it sounds worse than it is (this business of pressing the "Start" button twice). It all takes less than a second to do it prior to each pitch.
To the OP's request for sliders. I was hoping someone else would post theirs first. But when I get home later today I will post mine if nobody else has posted any. My slider setting seem to work reasonably well in my 4 MLB 14 MoM games to date. But what we need is for nomo17k to work his magic with his statistical evaluation of MLB 14 (like he has done in past iterations of the game). My sliders are tweaks of what nomo has recommended from last year. But my tweaks are not at all statistical. They are more of a gut feel.
Current MLB 14 sliders for MoM + CPU games:
CPU Contact: 5
CPU Power: 5
CPU Timing: 5
CPU Foul Frequency: 7
CPU Solid Hits: 5
CPU Starter Stamina: 6
CPU Reliever Stamina: 5
CPU Pitcher Control: 4
CPU Pitcher Consistency: 5
CPU Strike Frequency: 4
CPU Manager Hook: 3
Pitch Speed: 10
Fielding Errors: 4
Throwing Errors: 4
Fielder Run Speed: 4
Fielder Reaction: 5
Fielder Arm Strength: 3
Baserunner Speed: 5
Baserunner Steal Ability: 5
Baserunner Steal Frequency: 5
Wind: 5
Injury Frequency: 5