Back on January 22, Tom Verducci issued his annual "Year-After Effect" column. Dubbed the "Verducci Effect" by Will Carroll, the theory is that pitchers who are under the age of 25 and see a 30+ innings pitched increase over the prior year are at risk for a decline in performance or even injury.
However, the Verducci effect has been disproven time, after time, after time and is flawed at best.
So, should we be concerned that the Cardinals Joe Kelly was listed in Tom Verducci's column? Probably not. But that doesn't mean that there isn't something to Verducci's theory, even if it is flawed.
You old-schoolers, like me, might remember the 1980-81 Oakland A's starting rotation who went through two years of abuse from manager Billy Martin. For those of you who don't remember (or who weren't around at that time), Martin had an unreliable bullpen, but 5 good starters, so he pushed them to the limit.
In 1980, the 5-some of Rick Langford, Mike Norris, Matt Keough, Steve McCatty and Brian Kingman started 159 games and completed 93 of the (58%), pitching 290, 284.1, 250, 221.1 and 211.1 innings, respectively.
It continued in 1981, during the strike-shortened season, whereas the same 5 guys started 103 games and completed 59 of them (57%). Langford was the oldest at 28 in 1980, while Norris (25), Keough (24) and Kingman (25) were all 25 or younger (McCatty was 26). However, all of them suffered from the wear-and-tear of all those innings (and high pitch counts). Within a few years after the abuse they all suffered through injuries and had their careers cut short.
If we consider the A's example one extreme and the Verducci 30 IP minimum the other extreme, the answer probably lies somewhere in between. In addition, one has to consider pitch counts. If you have an efficient pitcher who throws 225 innings, but only averages 110 pitches per 9 IP (2750 total pitches), would he have more wear and tear than a pitcher who pitches 180 innings but averages 140 pitches per 9 IP (2800 total pitches)? The second pitcher has thrown 45 fewer innings, but has thrown 50 more pitches overall.
Nowadays, pitchers on put on strict innings limits (see Stephen Strasburg), pitch counts are monitored and pitching mechanics are adjusted all in an attempt to try to prevent injuries. Yet, despite all these efforts, pitchers will still break down each year.
In any case, Joe Kelly is probably safe from injury this year, but I do expect a decline in his performance, if only because his role is as yet undetermined.