A focused look at starting pitching data using Baseball Reference as the source. I reviewed by year from 1950 to the current season and averaged by decades the following data sets for the entirety of the major leagues : Average Innings pitched per start, average pitches per start (from 1988 to 2024 - no data (ND) is available prior to 1988), average complete games per team, average walks per nine inning (includes relievers - couldn’t find data specific to just starters) and average strikeouts per nine inning (includes relievers - couldn’t find data specific to just starters).
Innings Pitched Per Start :
The average starting pitcher innings length was relatively consistent from 1950 to 1979 sitting at 6.5 innings. That started to trend downwards from 1980 to 1999 falling to 6.1 innings per start - from 2000 to 2019 it dropped to a twenty year average of 5.8 innings per start and from 2020 to 2023 it fell to 5 innings per start - that’s held true to form so far this season as the average is 5.1 innings per start.
Pitches Per Start :
Data is only available from 1988 forward but it was relatively consistent till 2020 - the thirty two year average from 1988 to 2019 was 94 pitches per start. That’s trended down since as the average from 2020 to 2023 has fallen to 83 pitches. Discounting 2020 since it was a shortened season the 2021 to 2023 average was 84 pitches - so far this season the average is 85 pitches.
Complete Games Average per team :
Way back in the day when pitching staffs were smaller in regards to roster slots allotted complete games were more frequent. During the 1950’s teams averaged 52 complete games per season. That started to trend downwards over the next twenty years (1960-1979) as it went to an average of 40 per team. That was halved from 1980 to 1999 as complete games fell to an average of 18 per team. From 2010 to 2019 it was more than halved as the average fell to 5 per team over those twenty years. It’s dropped now to a rare occasion - the average complete games per season per team since 2020 stands at one.
Walks and Strikeouts :
Since starters average pitch counts held relatively steady from 1988 to 2019 I was curious why innings pitched per start were dropping. I looked at walks and strikeouts. Average walks per team per nine innings from 1950 to 2023 have held relatively steady at 3.3 (the 50’s era at 3.6 and the 90’s era at 3.5 being the outliers) so that doesn’t seem to be a root cause. However, average strikeouts per team per nine innings have continually trended upwards. From 1950 to 1989 the average strikeouts per team per nine innings was 5.2. There was with a big spike initially from 1990 to 2009 (an average of 6.4) and even more in the last 14 years (2010 to 2023) with an average of 8.3 - the data indicates that the drop over time in innings pitched per game by starters correlates - in general it takes more pitches to rack up K’s. Of course the build up of bullpen specialists also has had a huge play - the strikeout numbers include those hammered by high velocity and/or high spin rate reliever arms that can pitch more than once every five days - the data is indicative of that as well. That’s likely why the average pitch counts of starters per start since the 2020 season have now fallen into the mid 80’s range and IP per start also continues to trend downwards.
It’s only data - just thought ya all might be curios like I was is all.
Happy Day, Happy Baseball ⚾️
Here’s the complete breakdown of the data :
IP Avg per start - Avg Pitches per start - Avg CG per team - Avg BB/9 - Avg K/9
Four Year Average (2020-2023) - 5.0 - 83 -1 - 3.3 - 8.8
Ten Year Average (2010-2019) - 5.7 - 93 - 4 - 3.1 - 7.9
Ten Year Average (2000-2009) - 5.9 - 95 - 6 - 3.4 - 6.6
Ten Year Average (1990-1999) - 6 - 95 - 12 - 3.5 - 6.2
Ten Year Average (1980-1989) - 6.2 - ND - 24 - 3.2 - 5.3
Ten Year Average (1970-1979) - 6.5 - ND - 41 - 3.3 - 5.2
Ten Year Average (1960-1969) - 6.4 - ND - 40 - 3.1 - 5.6
Ten Year Average (1950-1959) - 6.5 - ND - 52 - 3.6 - 4.5
Year - IP Avg per start - Avg Pitches per start - Avg CG per team - Avg BB/9 - Avg K/9
2024 - 5.1 - 85 - 0 - 3.5 - 8.7
2023 - 5.1 - 85 - 1 - 3.3 - 8.7
2022 - 5.2 - 85 - 1 - 3.1 - 8.5
2021 - 5.0 - 83 - 2 - 3.3 - 8.9
2020 - 4.8 - 80 - 1 - 3.5 - 9.1
2019 - 5.2 - 86 - 2 - 3.3 - 8.9
2018 - 5.4 - 88 - 1 - 3.2 - 8.5
2017 - 5.5 - 92 - 2 - 3.3 - 8.3
2016 - 5.6 - 93 - 3 - 3.1 - 8.1
2015 - 5.8 - 93 - 3 - 2.9 -7.8
2014 - 6.0 - 96 - 4 - 2.9 - 7.7
2013 - 5.9 - 95 - 4 - 3.0 - 7.6
2012 - 5.9 - 95 - 4 - 3.1 - 7.6
2011 - 6.0 - 97 - 6 - 3.1 - 7.1
2010 - 6.0 - 97 - 6 - 3.3 - 7.1
2009 - 5.8 - 95 - 5 - 3.5 - 7.0
2008 - 5.8 - 95 - 5 - 3.4 - 6.8
2007 - 5.8 - 94 - 4 - 3.3 - 6.7
2006 - 5.8 - 94 - 5 - 3.3 - 6.6
2005 - 6.0 - 95 - 6 - 3.2 - 6.4
2004 - 5.9 - 95 - 5 - 3.4 - 6.6
2003 - 5.9 - 94 - 7 - 3.3 - 6.4
2002 - 5.9 - 95 - 7 - 3.4 - 6.5
2001 - 5.9 - 95 - 7 - 3.3 - 6.7
2000 - 5.9 - 97 - 8 - 3.8 - 6.5
1999 - 5.9 - 96 - 8 - 3.7 - 6.5
1998 - 6.1 - 97 - 10 - 3.4 - 6.6
1997 - 6.0 - 96 - 10 - 3.5 - 6.7
1996 - 6.0 - 96 - 10 - 3.6 - 6.5
1995 - 5.9 - 94 - 10 - 3.6 - 6.4
1994 - 6.1 - 97 - 9 - 3.5 - 6.2
1993 - 6.1 - 95 - 13 - 3.4 - 5.8
1992 - 6.2 - 95 - 16 - 3.3 - 5.6
1991 - 6.1 - 95 - 14 - 3.3 - 5.8
1990 - 6.1 - 93 - 16 - 3.3 - 5.7
1989 - 6.2 - 94 - 19 - 3.2 - 5.6
1988 - 6.4 - 96 - 24 - 3.1 - 5.6
1987 - 6.1 - ND - 22 - 3.4 - 6.0
1986 - 6.2 - ND - 22 - 3.4 - 5.9
1985 - 6.2 - ND - 24 - 3.3 - 5.4
1984 - 6.3 - ND - 24 - 3.2 - 5.2
1983 - 6.3 - ND - 29 - 3.2 - 5.0
1982 - 6.2 - ND - 28 - 3.2 - 4.7
1981 - 6.2 - ND - 20 - 3.1 - 4.8
1980 - 6.3 - ND - 33 - 3.1 - 4.8
1979 - 6.3 - ND - 35 - 3.3 - 4.8
1978 - 6.5 - ND - 40 - 3.3 - 4.8
1977 - 6.3 - ND - 35 - 3.3 - 5.2
1976 - 6.5 - ND - 43 - 3.3 - 4.8
1975 - 6.5 - ND - 44 - 3.5 - 5.0
1974 - 6.5 - ND - 45 - 3.3 - 5.0
1973 - 6.6 - ND - 44 - 3.4 - 5.3
1972 - 6.7 - ND - 42 - 3.2 - 5.6
1971 - 6.6 - ND - 45 - 3.2 - 5.4
1970 - 6.4 - ND - 36 - 3.5 - 5.8
1969 - 6.4 - ND - 41 - 3.5 - 5.8
1968 - 6.6 - ND - 45 - 2.8 - 5.9
1967 - 6.4 - ND - 39 - 3.0 - 6.0
1966 - 6.3 - ND - 37 - 2.9 - 5.9
1965 - 6.3 - ND - 37 - 3.1 - 5.9
1964 - 6.3 - ND - 40 - 3.0 -5.9
1963 - 6.5 - ND - 43 - 3.0 - 5.9
1962 - 6.4 - ND - 42 - 3.0 - 5.8
1961 - 6.4 - ND - 41 - 3.4 - 5.5 - went to 162 games from 154
1960 - 6.4 - ND - 40 - 3.5 - 5.3
1959 - 6.5 - ND - 46 - 3.4 - 5.2
1958 - 6.4 - ND - 46 - 3.3 - 5.1
1957 - 6.4 - ND - 47 - 3.3 - 5.0
1956 - 6.4 - ND - 47 - 3.3 - 4.8
1955 - 6.3 - ND - 47 - 3.7 - 4.7
1954 - 6.6 - ND - 52 - 3.7 - 4.2
1953 - 6.5 - ND - 54 - 3.5 - 4.2
1952 - 6.8 - ND - 59 - 3.6 - 4.2
1951 - 6.7 - ND - 59 - 3.8 - 3.8
1950 - 6.7 - ND - 62 - 4.1 - 3.9
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