These are all fairly logical choices with Evan Meek and Jose Ascanio still on the 60-day DL and several prospects still waiting to be added before the Rule 5 draft, as well.
At 27, Virgil Vasquez is little more than a vaguely convenient guy to have on your AAA roster--homers ate him alive in his 14 appearances with the Pirates this year, just like they did in his major league debut in 2007. There's no real reason to think that will change.
I liked Hacker a little when the Bucs acquired him from the Yankees for Romulo Sanchez, but he didn't do much with the Pirates to justify my continued interest. His line at Indianapolis (132.3 IP, 4.49 ERA, 94 K, 50 BB) was boring enough to place him squarely in that group of pitchers in their mid-20s who are nice to have, but only because they can start. He's another Vasquez, in other words.
As for Steven Lerud, the reason he was on the 40-man in the first place was not really because of his performance, but because catchers, and especially left-handed catchers with power potential, were in high demand. This season he made strides in controlling the strike zone, but the power mostly disappeared, and he continued to struggle hitting for average. He now has a career minor league average of .228, which means that unless he improves that and fast, he'd struggle to crack .200 in the majors. If he doesn't wind up in an another organization next year, he'll probably be back at Altoona for a third season.