Overpaying for a Bird and a Song

Last week, the Giants decided to move Jordan Hicks to the bullpen and Hayden Birdsong to the rotation. While some fantasy managers had already stashed Birdsong, he was available in many leagues like these nine NFBC Main Event leagues.

These teams spent 15% to 20% of their yearly budget on a starter projected to be below replacement-level. Unless a manager wore blinders or took some analyst’s hype without any doing their own basic analysis of Birdsong. No line of reasoning points to Birdsong making a difference, and the most likely scenario is that he’s on the waiver wire in a couple of weeks.

First, here are his projections that have him starting and relieving.

His 4.49 botERA (based on botOverall) is the most predictive of future ERA. Nearly in a row, his 3.66 SIERA, 4.29 xFIP, and 4.72 FIP emerge as better predictors. Each is well ahead of his ERA.

To see how much his stats should degrade as a starter, I compared the results of pitchers who spent time between starting and relieving (2021 to 2024, 5 GS, 10 relief appearances).

Using these values, Birdsong would see a 3.35 ERA, 4.99 FIP, and 4.74 xFIP. And the FIP and xFIP are more predictive than just ERA, so they point to a near 5.00 ERA.

The only variables that made sense to base this overbid on were the nearly 2.00 ERA and 25% K%. Here is how four pitchers, with simple reliever strikeout rate and ERA, performed as starters.

The prediction got worse with the best case scenario being a low-4.00 ERA

Of the 107 players who transitioned between starting and relieving, I found the strikeout rate the best predictor of future results. Here are those values plotted against each other with the predictive formula.

Birdsong has a 24.8% K%, and using the best fit line’s equation, he is projected for a 4.30 ERA as a starter. The number matches his average ERA projection. Everything points to him being a ~4.25 to 4.50 ERA talent. Even in these deeper NFBC leagues, similarly talented below-average starters are available on the wire.

Of course, Birdsong could be in that 30% of starters who outperform their relief number. This reasoning could be used for any starter. The goal over a fantasy season is to make as many positive process moves, and the good results will override the bad results. I’d rather take a similar chance on four to five $40 arms beating the odds.

For example, Slade Cecconi went on average for $41.5 in the NFBC Main Event and projects better than Birdsong. J.T. Ginn also projects for a 4.50 ERA and was added for $28.3. Another is Ryne Nelson, with a projection closer to 4.00 ERA, who went for an average of $28.7. Mid to low 4.00 ERA talents are always available. There is no reason to spend 20% of a budget on one.

I have no idea where the high bids for Birdsong originated, and I’m glad I don’t take their advice. If Birdsong was the only arm available, maybe the high cost would be worth it, but several similar or better arms were available at lower costs.