My last look at the bullpen covered the entire season to date, but I did get an email suggesting that the "tiredness" in question was not so much for the year overall, as the horrendous workload imposed on our relievers of late. There certainly does seem to be some evidence for that, if we focus our attentions on the period from May 19-27. Thanks to the double-header, we and the Marlins played ten games in that nine-day period; thanks to three of Arizona's going beyond the regulation nine, that meant a total of 95 innings of work for our pitchers. That's tied with Florida for most, with the Chicago Cubs next, back on 84.
The difference is even more extreme, if we break it down to the work of the relievers over the same time-frame. This took a bit more data-mining, involving the Play Index at Baseball-Reference.com, a spead-sheet and a well-oiled dolphin [though the last-named was more an entertaining distraction than any real help] - but I finally came out with the table below. This lists, for every bullpen in the National League, their workload from May 19-27, including the number of innings pitched, the results, pitches thrown, batters faced and relief appearances in total.
That paints a pretty stark picture: almost four innings per day. Even though preceded by two days off, our bullpen threw nearly 150 pitches - basically, the equivalent of an entire game or more - above the league average workload for the time. Admittedly, this pales beside the Marlins, who threw over 200 pitches more than even the Diamondbacks, but it does go a long way to explaining the poor performance of the bullpen. It's no coincidence that us and Florida have almost the worst ERAs in the league [the Rockies figure is bloated by one spectacularly inept inning against the Dodgers which resulted in eight runs, 40% of their total].
The deeper we got, the more it became a case of, not "Which pitcher is best for the situation?", but "Which pitcher does not currently have his arm held on solely by a small flap of skin?" The Padres series was the result, where the bullpen posted this line, which only their mothers could look at with anything but revulsion:
Bullpen: 8.2 IP, 16 H, 6 BB, 2 HBP, 6 K, 1 WP, 11 ER, 11.42 ERA
Hopefully, the worst is now over; eight innings last night from Haren will certainly have helped, though we are probably still hoping to avoid too much bonus baseball for the time being.