In any other division this wouldn't even be a conversation. However, each team in the NL Central has their own struggles that have kept them from running away with the division. After 74 games the Pirates sit at 37-37. First we're going to examine the Pirates challenges and successes then I am going to rate them on a 1-10 scale to express the likelihood that they reach the playoffs.
Pitching: The Pirates have a team ERA of 3.56, good for 1st in the division and 6th in the league. It is clear to see that this is their overall strength. Closer Joel Hanrahan has 20 saves and a WHIP under 1 in 34 innings. There are a couple concerns facing them as the season goes on though. James McDonald and Charlie Morton, while not the best pitchers on staff, are young and may tire near the end of the season. As usual, Pitt has been limiting their pitches per game but it will still be surprising if both of them can remain effective while reaching career bests in innings thrown. Also, Jeff Karstens seems to be over performing significantly. Maybe this is just the kind of pitcher he is and he's finally finding his form or maybe career bests in nearly every statistical pitching category is above his actual level of play throughout a season.
Outside of their pitching I cannot identify any other glaring successes. It has been the pitching that has kept the team at .500 to this point.
Hitting for Power: Obviously, when you look at their pitching and see great performances but no wins for their starters it becomes clear that offense is their main struggle. Andrew McCutchen has the most homers with 10. Even when you only consider doubles or triples they still rank near the bottom of the NL. No one on the team is batting .300. I could go on and on but really this team can't hit. Pedro Alvarez, Neil Walker and Lyle Overbay are all three much less productive so far than last season. And the team is still playing Ronny Cedeno at shortstop. Before the season many people speculated that Alzarez was a .300 hitter and Walker was a 15-20 homer infielder over the course of a season. Unless that actually starts to happen the Pirates won't creep many games over .500.
Fortunately for the Pirates they play in the NL Central which typically has 3-4 teams in the race. Right now the Pirates are only 3 games away from Milwaukee who is in first place. The month of July is going to be very telling for Pittsburgh when they play 15 games against division teams. If they can hang on through that month to stay at the top of the division then it is likely they hang in there through the end.
My score for the Pirates sits at a 3 in terms of their probability to make the playoffs. I predict they will finish ahead of the Cubs and Astros and possibly the Cardinals but not the Brewers or Reds. Those two teams will be fighting it out down the stretch for the division crown. Because of their younger pitchers and their under-performing position players this will not be a surprise playoff appearance for the Bucs.