Coming off of another bad outing on Sunday, this time against the lowly Orioles, there are rumblings that the Red Sox may have John Smoltz on a short leash. There’s even some chance that the veteran will lose his rotation spot when Tim Wakefield comes off of the disabled list in the next week or so. In six starts, Smoltz has a 7.04 ERA, and is averaging barely more than five innings an outing; he has yet to post a quality start. Driving the discussion is that the Red Sox have lost five of his six starts, and fallen from first place to second and 2½ games behind the Yankees since Smoltz was activated.

As I’ve hammered home, when it comes to Smoltz, there have generally been two poles in his performance record: effective and unavailable. Since his rookie season in 1988, when he ran a 5.48 ERA in a dozen starts for a Braves team going nowhere, Smoltz’s worst seasonal ERA is 4.14, that posted in the strike-shortened, offense-happy 1994 campaign. ERA+ is a statistic that measures a pitcher’s ERA relative to the league, adjusted for his home park. Smoltz, since 1989, has never posted an ERA+ below the league average. He’s missed entire seasons, he’s missed broad swaths of other seasons, he’s jumped from the rotation to the bullpen and back, but John Smoltz hasn’t pushed his team away from contention since we were all sweating Michael Dukakis.

Although Smoltz’s ERA is sky-high, he’s pitching more or less as well as he did last year, in his injury-shortened campaign, and even in 2007, when he finished sixth in NL Cy Young Award balloting. Smoltz has a stellar 28/5 strikeout-to-walk ratio, and his home-run rate, while elevated in 30 2/3 innings, isn’t that out of line with his career norms. The league is hitting a whopping .380 against Smoltz on balls in play, a figure that is driving his ERA higher and creating the perception that he might be done.

Let’s look at Smoltz’s last three seasons (’09 inclusive), by considering events as a percentage of batters faced (all statistics exclude intentional walks):

Year   BFP     K     BB    HR     1B   2B+3B
2007   777   25.4   4.9   2.3   17.5     5.4
2008   116   31.0   6.0   1.7   12.9     6.9
2009   139   20.1   3.6   2.9   17.3    10.1

As you can see, Smoltz’s strikeout rate is actually down a bit relative to recent seasons, and by enough compared to his last full season to cause some concern. His walk rate is down a bit as well, and he’s allowing homers and singles about as often as he did in 2007. The big change is on in-play extra-base hits, which have become far too common for Smoltz, especially considering that he has not seen a change in his fly-ball rate. This is the kind of number that can be affected by luck, and given that it’s the only truly bad number in his line, and the main reason for his high ERA, there’s every reason to think he’ll be fine.

Are there scouting-level reasons to be concerned? According to the data at Fangraphs, Smoltz’s fastball velocity is down a tick, from 92.5 mph to 91.5, and his slider velocity down a bit more (86.4 to 84.8). I would question, especially over a small sample from a rehabbing pitcher, whether those figures are significant enough to warrant much concern. Smoltz isn’t being hit notably harder-his line-drive rate of 19.6 percent is actually a bit under his career 20.2 percent mark. The only conclusion that can be reached from the available data is that Smoltz is essentially the same pitcher he’s always been, and has been victimized by a combination of poor defense and bad luck so far.

This is somewhat subjective, but I think there’s something to the idea that a pitcher who is giving up more of his runs in big innings is a better bet going forward than one who tends to give up runs in more innings. The former pitcher is usually effective, but he may be tiring quickly, or prone to slipping into a mechanical problem, or has just been unfortunate. Smoltz has been an extreme example of the type. In four of his five bad starts, he’s basically been knocked around in one inning. In one of those, July 21 against the Rangers, that one bad inning was allowed to go on interminably despite Smoltz’s rapid degradation in performance in the sixth. Most of the time he’s taken the mound, Smoltz has walked off it having succeeded in holding down the other team. It’s the one bad inning that has haunted him.

If there’s a potential landmine, it’s in that high BABIP number. The idea that pitchers have limited control on the results of balls in play applies to major-league hurlers. A pitcher who has slipped below that level will sometimes have a high BABIP because he’s allowing balls to be hit so hard and so far that he’s indefensible. This is a possibility, but with all the scouting and ball-in-play data showing very little change, the more likely result is that Smoltz has simply been unlucky. His baseline performance-striking out batters, allowing few walks, and a reasonable home-run rate-tells the true story. The Red Sox should stick with Smoltz as a starter, as he’s the fourth-best one on their roster.