I know there are a lot of people looking at Mark Reynolds' .198 average and huge strikeout total from last year and wondering why the Orioles acquired such a flawed player to start at third base, but it's not that complicated.
Andy MacPhail needs to inject some power and run production into the Orioles lineup and he came up a little short on Victor Martinez, which left him with a list of available players that all have some kind of drawback. Personally, I would have been happy to take Adam Dunn and split him between first base and DH in spite of his strikeout total, but he's got some of the same issues as Reynolds and he got $56 million from the White Sox.
The other big power option is Carlos Pena, who had an even lower batting average than Reynolds and also strikes out a ton. The Orioles haven't ruled out adding him, too, and getting Reynolds cheap makes that possible. I'm not sure what to think of injecting a potential 65 home runs and 360 strikeouts into the O's lineup, but I'm guessing that would be more entertaining than what you've been seeing the last decade or so.
In defense of Andy, sometimes you don't get to do what you want, so you do what you can.