Tanner Bibee, Where are the Whiffs?
Bibee’s K% and Whiff% is way down, lets try and find out why.
Before I get into this, I need to make it clear that I am not worried about Tanner Bibee. I have no doubt that the issues I am pointing out will be remedied sooner rather than later.
Tanner Bibee so far in 2025 has seen an 8 point drop in whiff% taking him from the 61st percentile in 2024 down to the 17th in 2025. He is getting about 7% less chase as well, though that was never his strong suit. These two factors have brought his K% down 10 points from the 74th percentile all the way down to the 15th.
What changed?
One big change was the addition of a sinker to his arsenal. Bibee uses the sinker about a quarter of the time against RHB and about 7% of the time against LHB. The sinker is not intended to induce whiffs, the intention of it’s introduction to his arsenal was to limit hard contact and get more ground balls which has worked decently well. Bibee’s ground ball rate is up from the 10th percentile up to league average and he has dropped his line drive rate well below league average.
Bibee’s fastball was already an issue last season, this year it has only gotten worse. The fastball used to grade out about average whereas so far in 2025 it is below average. He is getting less whiffs, less chase, and throwing less strikes with the 4-seam this year.
His other pitches have maintained the same stuff grades yet they have all seen a decrease in whiff% as well. I believe this can be attributed to the 4-seam fastball.
Bibee has cut his 4-seam usage by about 10% but it is still his primary pitch, especially against LHB (40.4%). With its diminished shape, batters are not being forced to respect the fastball anymore, allowing them to hit the offspeed and breaking pitches more. This is only exacerbated by the fastball being in the zone just 48% of the time.
Tanner Bibee could really benefit from reviving his 4-seam, if that is possible. Something I found while digging into the pitch was a change in spin axis from last year. The spin axis on the 4-seamer has decreased just a little bit, possibly enough to explain the diminished shape, and I believe that the sinker might explain why.
The spin axis on his fastball is now the same as it is on the sinker, whereas in 2024 (small sample) the 4-seam had a higher spin axis than the sinker. I think it is entirely possible that the release of the two pitches is blending together for Tanner. This theory is backed up by the decrease in ride and increase in run on the 4-seamer.
Tanner’s sinker is still new, so it isn’t surprising that there are adjustments needed and things to learn. I wouldn’t be overly worried about this for Bibee as it seems like a relatively simple mechanics adjustment can have a big impact going forward.
Let me know what you have seen with Tanner Bibee and if you have anything to add to my analysis!