When Kevin Towers traded for Heath Bell, no one was under any illusions that he would be worth his $10M per year salary in 2013 and 2014, even if there was hope that his 2012 was just a down year. With Miami paying $4M per year, it’s probably fair to say that Towers hoped Bell would be worth $6M per season.* The truth is that he’s been worth less than the major league minimum.

Why less? I’m not saying a minor leaguer would definitely have done as good or better than Bell (although FanGraphs has Bell’s season at exactly replacement level, with 0.0 WAR). Saying that would just be saying that Bell was only worth the major league minimum, but that he actually was worth that amount. Think about it, though: if a minor leaguer had struggled the way Bell struggled, he could get sent down and replaced with ease. He would get sent down and/or replaced. That’s the double curse of buying veteran bullpens — the inflexibility that comes with the significant payroll obligations.

Because the value of relievers tends to fluctuate so wildly, flexibility in that part of the roster is to be prized more there than it might be for an outfield crew or a starting rotation. Flexibility has a very real value in roster construction generally, but its value in the bullpen is significant.

The best nugget I got from reading I, Claudius as a kid was the narrator’s thoughts on monarchy. The novel explains Claudius’s terrible turn at the end of his reign as Emperor by giving the fictional character a wish to force his subjects to prefer democracy. He was afraid that by being a good monarch, he was leading his subjects to love monarchy — and he wanted democracy returned to Rome. Claudius (the character) believed that a good monarchy was better than a good democracy — but that a bad monarchy was far worse than a bad democracy. Maybe no democracy can be as disastrous as a dictatorship helmed by a tyrant.

If money was absolutely no object and you could afford to keep signing expensive relievers (cutting the ones who struggled), then a bullpen made up of veterans has a much greater chance of being great than a bullpen composed mostly of young relievers. But a bad bullpen of young guys is a much better situation than a bad bullpen of veterans. A bad bullpen of veterans with salaries too big to waive is the worst case scenario.

This preference for a young bullpen is independent of the fact that veteran bullpens are more expensive. The preference is solely about flexibility.

Veteran bullpens are more expensive, though, and that is a second important reason to avoid them. I projected a $99.8M payroll for 2014 without accounting for possible transactions. Bell will make $6M, J.J. Putz will make $7M, and David Hernandez has $2.125 guaranteed. Matt Swartz of MLB Trade Rumors projects Brad Ziegler at $5M, Joe Thatcher at $2M, and Josh Collmenter at $900k. Including $500k for Will Harris but excluding all of the major league salaries for relievers that will inevitably be added during the course of the season, that’s about $23.5M. In my $99.8M figure I included credit for five other ML minimums for pitchers, so make that $26M.

Yes, a bullpen is almost a third of a major league roster. But pitching is only one half of a roster, and a bullpen is responsible for less than half of the pitching half — in 2013, the D-backs had 518.2 innings from relievers but 976.1 innings from the rotation (1485 overall). The bullpen was responsible for 34.9% of the team’s pitching innings in 2013, a year that featured a ridiculously high number of extra innings. But using that number, it seems that a bullpen is about 17.5% of how games get affected. Considering we’re looking at dedicating $26.0% of the 2014 payroll there, that’s pretty out of whack. Going cheaper than 17.5% of the payroll (12%?) would free up a lot of room for upgrades elsewhere.

Of course, a young bullpen can be expensive in a different way, if a team gives up talent in a trade to get them, or if they pass on other options in the draft in favor of likely relievers. But, again, it is really only the most expensive of veteran relievers that are very good bets to be consistently above average, due to the high variability of performance for relievers. So give me a near-replacement level rookie over a $5M reliever any day of the week — unless, maybe, that $5M reliever is undervalued and is a guy who’s shown a talent in groundball rate.†

Maybe the biggest hangup I wish Arizona and other teams would bypass in terms of building a bullpen from within is the fear that young pitchers would get underutilized in relief. Generally speaking, I think the industry is a little too concerned about making sure players get used in roles that maximize their usefulness. Backup catchers are usually a good example of this — if a catcher shows a likely ability to handle full time duties, but is blocked from doing so, he usually gets traded (like Wilson Ramos in 2010).

There is a very real possibility, for example, that Andrew Chafin could be a good, productive major league starter, as Jeff recently explained. I absolutely agree that he should get more of an opportunity to develop as a starter; throwing more pitches can only help his development anyway, and if can end up a solid #3 starter, I agree wholeheartedly with Jeff that he’d be much more valuable to the Arizona organization as a starter than as a reliever. But if in 2015 it really doesn’t look like there’s room to try him in the rotation, we should be thrilled about the possibility of seeing him in relief. Good relievers are valuable too, especially in contrast to an overpaid veteran — and as “relief prospects” go, it may be that a higher quantity of the promising guys have profiles more similar to Chafin’s than to guys like Jake Barrett. Yes, it’s easy to be in a situation like that of St. Louis, and believe that both Trevor Rosenthal and Carlos Martinez are greatly underutilized assets as relievers. But since they’re definitely valuable that way, it might not be worthwhile to flip an organization on its head or trade away legit starters to create opportunities. Just ask Boston how that turned out with Daniel Bard.

In the end, the ideal bullpen probably has a mix of ML minimum salaries and a few pitchers who make more, but less than market rate (guys with 3-5 years service time, for the most part). A reclamation project or two would also make sense, given that such guys could sign bel0w-market, short-term deals in exchange for playing time to help justify a subsequent deal.

I’d just hate to continue seeing the team bleed money from the bullpen while strangling itself at the same time. If the D-backs sign a non-Ziegler reliever for more than $4M per season during the next few months, don’t expect to see anything up on this site about it right away — it’s hard to type while screaming into a pillow.

*On the day that Bell was acquired, the D-backs actually cut back their 2013 payroll obligations. They sent Chris Young’s $8.5M salary to Oakland with a $500k offset in exchange for the 2 year/$5M contract of Cliff Pennington ($1.25M for 2013) and the “prospect” who got traded to Miami for Bell. Still, because it’s not clear that Oakland would not have made that Chris Young swap but for Arizona’s Bell deal, I still think it’s fair to say Towers valued Bell at $5M per season.

†Call this the “Ziegler exception,” and yes I just made that up to serve my own argument. Even in the face of a large general overvaluing of relievers, some guys can be undervalued to the point of still being a good use of dollars. Ziegler’s ground ball rate was the best in the majors last season, and only Seth Maness of the Cardinals came relatively close. If Ziegler’s ground ball rate dominance was switched for dominance in the other most sustainable and predictive pitching category (strikeouts), he would cost a lot more, don’t you think? NB: If there was an undervalued reliever who was a dominant strikeout artist, he’d also fit into the “Ziegler exception” for me, because strikeouts, like ground balls, tend to be both sustainable and predictive. It’s just that dominance in ground ball rate is much more likely to be undervalued.