The last couple of days, I've been looking at my roster indecisively, trying to decide how best to use the 25th spot for the playoffs.  I can't decide whether to spend it on a contact hitter with a little bit of speed or a guy who mashes v LHP with a little better glove.  I should note that I already have 2 bench players who can cover 2B/CF/SS (both of whom are fast but with baserunning skills in the 60s), a low batting-eye/high power guy who strikes out a lot but kills RHP and plays RF, and a solid backup catcher.

I could make the decision myself, but I thought it might be instructive to hear how others reasoned this out.  The guys are:

http://www.whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=2928266

and

http://www.whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=1019145

First thing that comes to my mind is if your opponent has lefty starters or a lot of lefties in the pen.
I like the 2nd guy better, but if you expect to encounter a lot of lefties that might swing it towards the first guy.

First guy to me seems worthless...

If I understand correctly, you have an NL team and are planning on using 13 position players. Without spending too much research time on your team, I'd suggest that you consider whether or not you really need your 12th pitcher. 12th pitchers are rarely of consequence in the playoffs. So, unless you can't bear the thought of being exposed to fatigue from multiple extra-inning games, problem solved.

I opted for guy #2...playoffs started today.  This is the first time that I've made the playoffs...I wasn't even thinking about the possibility of dropping a pitcher.  I wish I'd asked this question earlier, because my 12th P is kind of marginal anyway.  I'm not sure if I can switch my playoff roster around after playoffs have started?  I keep thinking about giving guy #1 a chance because players with similar numbers to him seem to be leading my league in HRs, or at least in the top 10. 

You can switch between rounds if you win to continue playing.