Obviously, I don't understand how the mop up pitcher works.  I assumed that the mop up guy would be used by the computer when my team was getting pummeled, saving the rest of my bullpen from getting tired.

        However, my mop up pitcher keeps appearing in late game, close game situations, My latest game was tied going into the bottom of the ninth, and my mop up pitcher came in to lose the game. Meanwhile I have three setup pitchers at 100% and my closer available. I have my settings set to use mop up only when losing. So, how does this sort of thing keep happening?

I wonder the same thing. Every once in a while my mop up will come in late in a close game and blow it for me too?

A few possibilities:

1.) Did you check the box for "use closer in save situations only"?  If you did, then your closer will not come into a tie game.
2.) Are you sure that your setup guys and closer were 100% prior to the game in question?  And what autorest setting do you use for them?  I would guess that at least 90% of the time that this situation has come up in the past, it turns out that the other pitchers were fatigued below their autorest when the game started (they may be back up to 100% now, of course).  Had any of them pitched in the previous game?  If so, it's quite likely they were not at 100%. 

In my experience it's very unusual for WIS to use a mop-up in a non-mop-up situation if other pitchers are available and rested.  It could happen, but almost all the time there is a specific reason why other pitchers were not used.

If all else fails, send in a support ticket, and WIS may be able to tell you why this happened.

I bumped a thread called "How Sparky Uses His Bullpen" that I started a few months ago; it may or may not be useful info.

There is no rhyme or reason as to when the mop-up guy comes in that I can see.  contrarian23 is right on all counts, but even with those intangibles set correctly I've had mop-up guys blow enough games for me that I don't even use it anymore.  I still say there should be an option for mop-up, such as "When losing by "X" or winning by "X", use mop-up". Seems to me that would correct all the guess work.

Your mop up may come in depending on your settings if:
1) You are being blown out
2) You are blowning out the other team
3) He is the last reliver "available"

Independent of your settings, your mop-up will ocasionally enter a game if:
4) He is substaintially under worked compared to other relief pitchers.

#4 is obviously key here.  The solution is to find work for your mop-up.  That could mean promoting him to a long b with a pull of 5, or better yet start him in the ocasional intentionally blown game.

 

Given all the vagaries of Sparky's 'intelligence', I rarely use a mop-up.  Worst case, if I have a reliever who is just not working out I'll move him into that position rather than keep him on constant Rest.  The only other time I use mop-up is if Ihave a few hundred K left over; I'll get the best RP I can for that price and set him to mop-up some of the time and rest (to avoid zubinsum's Reason 4 above) some of the time.

If all yr other pitchers were used they`ll use mopup b/4 rested pitchers.

I used to get burned by the mop up man on occasion, to the point that I never use the setting much in a normal league.

However, in draft leagues, I will take a poor starter and use him for mop up, and I've had very good results with this, allowing him to be used in games where I'm ahead as well as behind.  One such guy picked up several three-inning saves in blowouts, conserving my starters' innings for later in the season without taxing the key setup men.