FanPost

Trevor Rosenthal and 2014 Usage

There has been a lot of hand-wringing and angst and concern about the way Trevor Rosenthal has sometimes been used by Mike Matheny in 2014. First of all, Rosenthal has not been nearly as effective this year, as the closer full-time. Whether that is a result of his usage, a small sample size issue, a lack of command on the year, a decline in talent or work ethic, a lack of confidence, the pressure of the closer role, or something else entirely is unsure. Today I am going to take a look just at how he's been used and the effectiveness in those situations.


As of the morning on 7/21/14, Rosenthal has pitched in 46 games and thrown 46 2/3 innings. He has a 3.47 ERA, 2.78 FIP, 3.50 xFIP, and 3.16 SIERA this season. All in all, his ERA should be between 2.78 and 3.50 and it is - on the upper edge of that range - based on the way he's pitched this year. He has struck out an incredible 29.6% of the batters he's faced, but he's also walked 12.8% of them. The last two years, the difference between his K rate and walk rate were +20.2% in 2012 and +28.3% in 2013. This year, it is down to +16.8%. Because of the high walk rate, Rosenthal has a 1.35 WHIP in 2014, well above his previous 0.93 in 2012 and 1.10 in 2013. Furthermore, Rosenthal's GB% has severely declined from 2013 to 2014 and had already declined from 2012 to 2013, while his LD% has jumped considerably, now at over 26%! Not only that, but his LOB% has dropped 2% from 2013 and 3.4% from 2012, which is why there is such an increase in runs scored off of him this year.


In 30 of Rosenthal's 46 games this year, he has had anywhere between 1 day's rest and 6 days' rest (post-All-Star game), not including the rest before game 1 of the season. On 11 occasions, he has thrown a 2nd day in a row. On 4 occasions, he has thrown a 3rd consecutive day. AND on one occasion, he threw for a 4th consecutive day.


On days where Rosenthal has between 1-6 days rest, he has:

thrown 32 1/3 innings

faced 139 batters (4.3 per inning)

thrown 562 pitches (4.04 per batter and 17.38 per inning)

has a 3.34 ERA

and a K% of 28.8% compared to a BB% of 12.2%


On the 11 days that Rosenthal has had 1-6 days rest and goes on to throw games on consecutive days, he has:

thrown 11 2/3 innings

faced 52 batters (4.46 per inning)

thrown 212 pitches (4.08 per batter and 18.17 per inning)

has a 4.63 ERA

and a K% of 21.2% compared to a BB% of 13.5%


What's strange to me is that on the days before throwing more days consecutively, he has already thrown more pitches per batter and per inning than normal...and been less effective than normal.


On the 11 days Rosenthal has thrown on a second consecutive day , he has:

thrown 10 1/3 innings

faced 42 batters (4.06 per inning)

thrown 185 pitches (4.40 per batter and 17.90 per inning)

has a 2.61 ERA

and a K% of 31.0% compared to a BB% of 14.3%


On the 4 days Rosenthal has thrown on a third consecutive day , he has:

thrown 3 13 innings

faced 16 batters (4.8 per inning)

thrown 68 pitches (4.25 per batter and 20.4 per inning)

has a 2.70 ERA

and a K% of 37.5% compared to a BB% of 6.3%


On the one occasions Rosenthal has thrown on a fourth consecutive day , he has:

thrown 2/3 of an inning

faced 6 batters (9 per inning)

thrown 23 pitches (3.83 per batter and 34.5 per inning)

has a 27.00 ERA

and a K% of 16.7% compared to a BB% of 33.3%


Contrary to the LD% I spoke of above, which was found at Fangraphs; I got the raw data on LD, GB, FB, IFFB from baseball-reference, so here are his season-to-date percentages on those instead:


25.2% LD, 31.1% GB, 43.7% FB, 13.6% IFFB


On 1-6 days rest:

23.3/34.0/42.7/11.4


On 2nd day pitching in a row:

30.3/27.3/42.4/14.3


On 3rd day pitching in a row:

20.0/30.0/50.0/20.0


On 4th day pitching in a row:

40.0/0.0/60.0/33.3


As you can see, Rosenthal has been absolute rubbish pitching on his 2nd and 4th days in a row. He's been (quite possibly) at his best this year when throwing a 3rd day in a row. He's been bad (for him) throwing on 1-6 days rest.


On the days where he's gone a third consecutive day, he had thrown 43, 39, 29, and 25 pitches on the two previous days. That's an average of 34 pitches in the two prior days (plus warm up pitches). He had faced 9, 7, 8, and 6 batters - for an average of 7.5 batters per two games prior to the third game. That comes out to 3.75 batters per game and 17 pitches per game prior to throwing a third game - which isn't the worst usage in the world - minus the first time he went in when he'd faced 4.5 batters per game prior and over 20 pitches per outing.


The one time he came in on a 4th consecutive day, they gave him 2 days' rest afterwards - which was good to note. However, he had faced 12 batters and thrown 52 pitches in the previous 3 days. That's 4 batters and 17.3 pitches per inning for 3 consecutive days before entering that game. The interesting thing, I guess, is that on the 5 occasions he has gone 3 or 4 days in a row, Rosie has had 3 saves, 1 blown save, and 1 loss in a non-save situation. That % is not good. Considering in all other situations he has 3 blown saves in 30 opportunities, it looks even worse (60% sv rate compared to 90% normally).