It is no secret that the bullpen has been the most depressing aspect of the Royals' young season. However, based on the data available, I don't think the members of the bullpen (at least a few of them anyway) are as bad as we are making them out to be. The following is my amateur evaluation of the current bullpen staff.
Farnsworth doing what he does best. Also, the catcher looks really awkward.
I guess I'll start off with the obvious ones.
Joakim Soria is the man, and there is not really any question that he is the best pitcher out of the pen. There are some questions about Hillman's usage of the Mexicutioner, but as far as personnel goes, he's top notch.
On the other extreme, Luis Mendoza has no business being in a Major League uniform. He has a career xFIP of 5.20 in over 80 innings and has managed to post an astonishing -0.5 WAR in just 3 innings this year. Sure, it would be near impossible to stay that bad for an extended period of time, but he's still just not any good.
Roman Colon is in similar territory. Based on xFIP, Colon's best years were in 2004 and 2005 when he played for... dramatic pause... the Atlanta Braves. He had actually not pitched in the majors for three years before putting up a sub-replacement level season last year. The guy turns 31 years old this year, and there is really no reason to expect anything more from him than what we've already gotten: garbage.
Next on the list are a couple of relievers that are a little more enigmatic.
Dusty Hughes is a 27-year-old lefty who appears to have some useful tools. His big league experience is very limited, but he was an above average pitcher at every level in the minors. In AAA last year, he transitioned to being a reliever and posted a respectable K rate of of around 8 per game, but did walk just over 4 per game. He seems to be another pitcher who might suffer from being managed by Hillman. In 15 PA against him last year, lefties managed four hits, all singles, with no walks and five strikeouts. In 48 PA against righties, he surrendered nine hits, 2 of which were homers, 8 walks, 2 HBP, and 10 Ks. That is an extremely small sample size, but he does appear to have some skill against LHB and struggle against RHB. From what we know now, he looks like a guy who could be worth having around. The fact he will be mismanaged isn't really his fault.
The other lefty in the bullpen is the 32-year-old John Parrish. The veteran does not appear to have an overly dramatic platoon split. For his career he's posted a tOPS+ of 102 against righties and 95 against lefties. He was out of baseball last year, but pitched 42 innings for the Blue Jays in 2008, putting up a 5.11 xFIP in the process. In 2007 he earned an xFIP of 5.23 in 52 innings for the Orioles and Mariners. He has put up good numbers so far this year, but has benefited from a .000 BABIP. Given the Royals' lack of defensive skills, that number is due to skyrocket. From what I can tell Parrish is not likely to be very good, and if this wasn't the Royals I would be surprised if he managed to stay on the roster for the entire season.
Rounding out the trio of question marks is Robinson Tejeda. The age 28 Tejeda has been frustrating because of his inconsistency. He has shown signs of promise, but has also stunk up the place on occasion. He posted FIPs of 3.95 and 3.60 in 2008 and 2009, but his xFIP in both seasons hovered around 4.50. Last year, he had a career high K/9 of 10.63 but walked over 6 per game. He has the ability to start in a pinch, and his strikeout ability is great out of the pen, but his control will likely always be a problem. He can be lights out or blow up, but he is far from the biggest problem in the bullpen.
Juan Cruz has been the subject of trade rumors since spring training. He is 31 years old and has been a full-time reliever since 2007. In 2007 and 2008 he had a K/9 of over 12. His struggles last year were due to his K rate collapsing to 6 per game while maintaining the same BB/9 and HR/9 numbers. His BABIP this year has been almost .500, so his results have been more than a little unlucky. Through about 5 innings his K/9 is back up to 11.57 and I don't see any reason why he couldn't post an xFIP under 4.00. In fact his ZiPS projection pegs his FIP right at that level. If he performs at that level, he would be an above average relief pitcher, and a useful member of the bullpen. He gets a lot of flak because of his contract, but that is Dayton Moore's fault. Despite the animosity towards him, Cruz is a pretty decent pitcher.
Last, we get to none other than Kyle Farnsworth (or Farnsworthless as he is commonly referred to). Farnsworth has faced an uphill battle to win the hearts of Royals fans in large part because Dayton handed him an undeservedly enormous contract and he proceeded to blow several games early last season. He also suffered from a BABIP of .387 last year, which is the highest number of his career. Out of the pen he has a career xFIP of 3.78 including 4.04 in 2008 and 3.37 last year. The other criticism of Farnsworth is that he is not "clutch" or that he cannot perform in a close game. The numbers just don't jive with that analysis. For example in high leverage situations he gives up a home run about once every 50 PA and strikes out about 22% of the batters he faces. In low leverage situations, he gives up a home run about once every 30 PA and strikes out a comparable 24% of batters he faces. Also his postseason xFIP is 2.92, almost a full run lower than his regular season number (although he does only have 14 postseason innings). Farnsworth is actually another above average reliever who is a valuable member of our bullpen. In fact, he is probably the second best pitcher we have in the pen.
In conclusion, Soria is awesome, Cruz and Farnsworth are overpaid but actually pretty good, Hughes and Tejeda can be useful, Parrish is not likely to be very good, and Colon and Mendoza have no business in the major leagues.