Juggling Monkey: BP Says Relievers Inherently Replaceable

Now this might not be news to some people and I had heard this from other places before (I recall someone quoting Bill James, for one), but I wanted to at least source a reference to this in a post. In a column unrelated to relievers (marketing plug for new BP injury report), the author states this about relievers (in relationship to injuries):

In large part, I ignore bench players and relievers because they are
inherently replaceable. If a team loses a middle reliever, studies have shown that there's usually very little bottom line effect; certainly nothing like losing a closer or even a mid-line starter.

Now, I didn't quite always buy that rationale, and thus I was initially against the Nathan trade for the Zitster. Then to my undying shame, I supported the trade when some posters convinced me otherwise, whereupon I switched back to my feeling that relievers are important and are not easily replaced.

But over the past couple of years, as the minor league system has provided a steady stream of pitchers to the majors, I am juggling back to the position that relievers are inherently very replaceable. I guess you just need a good farm system to see that logic and not make mistakes like thinking Nathan was not closer material. Particularly when he was so dominating during the season (apparently his meltdown during the playoffs convinced somebody that Nathan was not closer material, and I guess, Herges was - to be fair, Herges was lights out that playoffs).

So, hence why I'm not so put out about the Giants not having the greatest of bullpens. Closer? Yes, a problem that I'm hoping someone - Wilson, Sadler, Anderson - will step up to the plate and own the position. But the rest of the bullpen, it seems strong enough to me, not the greatest but I don't think they will be the pits, and if they are, I think someone will get promoted from the minors and do well, eventually