If Jhonny Peralta were a Cardinal in 2014, what would he do? Well, he is, and there are some projections out there that do the maths and can help us know what to expect... unlike trying to expect where the "h" in his name is, which is rather unexpected, and always will be, every time I read it.
But anyway, Peralta is a huge upgrade over Pete Kozma, and marked the biggest move the Cardinals made in the offseason. The projection systems at fangraphs.com think he will get 11 to 14 home runs this year, which is pretty nice from a position that is usually rather light-hitting (looking at you, warlock). The average comes out to 13 home runs, but if he keeps doing what he did in spring training it could easily be more than that.
Peralta topped out at 136 wRC+ years ago in 2005, so we should temper our expectations... he has been rather spotty throughout the years, the lowest being 83 since then. That's a rather big swing, and he is a volatile player in trying to predict his offensive outcomes. The average projection here in this normalized stat is 105 wRC+, which is above average for all hitters and far and above what Pete Kozma would do.
His batting average and on-base % projections are not all that exciting, but they are decent at .267 BA and .323 OBP. That'll do, Jhonny, that'll do.
Moving beyond offense, his projections on defense are actually all above average, but not flashy by any means. To attempt to couple the two together to evaluate him as a complete player, fWAR is ok. His most optimistic WAR projection is from Fans, at 3.7. The average fWAR projection comes out to 2.6. Not super exciting, but it is a definite and obvious upgrade for the shortstop position for the Cards.