David Pinto over at Baseball Musings has this little note about Barry Zito's struggles this year.

I can only say that I wish I knew what was wrong with him. Perhaps, as Pinto suggests, he really is tipping his pitches. Maybe it's something more nefarious, like an injury. Maybe his world-renowned mental balance is off. Whatever it is, he's getting rocked repeatedly. This isn't something the A's need when they're already missing their best starter (I'm not talking about Mark Mulder) and their now-third-best pitcher (Rich Harden) is dealing with some shoulder issues (albeit not in his throwing shoulder; still, I imagine it's painful, and he's probably got to be extra careful that he doesn't let the pain throw his mechanics, and his already fragile control, out of wack).

Those Zito trade rumors don't sound so bad now, though there's, again, no way the A's get fair value for him today. Zito's got nowhere to go but up, so we'll just have to hope that he, Curt Young, and maybe his dad can get together and straighten things out.

There's also the thought that nobody wants to say, though: maybe Zito's done. Baseball is littered with flameouts, especially among pitchers, and not all of them are due to injury. While Zito's top PECOTA comparable is Steve Carlton's 1971 season (right in his prime, at age 26), on the list are also:

• Wilson Alvarez, 1996: it was his second-to-last good year, though he's enjoyed something of a renaissance recently;
• Lou Brissie, 1950: Brissie was great in 1948-1950, putting up 189 pitching runs above replacement [comparable to Zito's 232 from 2001-2003] before apparently being traded midway through 1951, seeing his performance blow up, and disappearing after 1953, at age 29. Turns out, according to this website, that Brissie had his leg blown apart in World War II, so that he pitched as well as he did was something like a miracle in the first place. Anyway, Brissie walked away from the game young rather than pitch in the minors again, so we can't really say whether he could have made a comeback.
• Mickey McDermott, 1955: McDermott put up a nice run from 1949 to 1955, starting at the tender age of 20, of PRAR: 23, 23, 52, 43, 70, 46, 50. Unfortunately, he never broke 100 innings pitched again, nor 15 PRAR, and he was out of the majors after 1961, at the age of 32. An elbow injury apparently slowed him down, and there are notes of 16- and 17-inning games pitched by McDermott in the early fifties, so perhaps the modern attention to health can keep Zito from this kind of trouble.
• A very alarming 1999 version of Justin Thompson. Thompson, as we know, hasn't pitched in the majors since that year and has, I believe, officially retired, though I can't find record of it.
• Dean Stone, 1956. Stone had put up 54 and 42 PRAR as a 23- and 24-year-old in '54 and '55, but managed just 3 in 51 innings the next year. He managed to stick around until 1963, though he didn't pitch in the bigs in '60 and '61. From '56 to '63, however, he managed just 24 PRAR in about 190 innings.

In other words, there's some alarming stuff there in terms of Zito's potential longevity. On the other hand, there are a number of guys who had four to six more productive years in the majors on the list as well, so perhaps the data's only alarming if you're by nature an alarmist (I am).

The most interesting comparison, though, was to Kevin Millwood's 2001. Millwood's been an overrated pitcher, certainly, as 1999 was his only truly excellent year, but he's generally been a nice solid pitcher, chugging along with 45, 90, 53, 25, 69, and 61 PRAR. You'll notice the two outliers there. The first is the aforementioned 1999. I'll give you one guess in which year the 25 PRAR came. I'm not being entirely fair, though, because Millwood pitched just 118 innings that year, a number that, unless Zito comes down with some health issue, Zito's very likely to pass.

Anyway, Zito's last three years has established a baseline performance much higher than Millwood's, but perhaps we can take some solace in his being compared to a guy who had one pretty bad year but bounced back quickly to his earlier levels of achievement.