Little known Pitcher is Tigers All-time Seasonal ERA+ Leader

Ed Siever had one of the best seasons ever for a Tigers pitcher in 1902 (Photo credit: TheBaseballPage.com)

Today, I am going to continue with the ERA+ theme by looking at the best individual seasons in Detroit Tigers history.  The Tigers have seen some outstanding pitching seasons over the years - Justin Verlander earning the Cy Young and MVP last season, Hal Newhouser gaining back-to-back MVPs in 1945-1946 and Denny McLain winning 31 games in 1968 to name a few.  However, The best season of all time according to the ERA+ metric may surprise fans who do not follow Tigers history that closely.

Table 1 below lists the top seasons by ERA for pitchers with 162 or more innings pitched.  The ERA+ and % columns are explained in an earlier post.  In 1902, the second season in the franchise's existence, southpaw Ed Siever posted an ERA+ of 197 in 188 innings of work.  That means his ERA was 49% lower than league average.  Siever remains the Tigers single-season ERA+ leader 110 years later. 

Table 1: Top Tigers Pitching Seasons by ERA+, 1901-2011

Player	Year	IP	ERA	ERA+	%
Ed Siever	1902	188	1.91	197	49
Hal Newhouser	1945	313	1.81	195	49
Hal Newhouser	1946	292	1.94	190	47
Hank Aguirre	1962	216	2.21	184	46
Al Benton	1945	191	2.02	175	43
Justin Verlander	2011	251	2.40	170	41
Bobo Newsom	1940	264	2.83	168	40
Dizzy Trout	1944	352	2.12	167	40
Hal Newhouser	1942	183	2.45	162	38
Hal Newhouser	1944	312	2.22	159	37
Mark Fidrych	1976	250	2.34	159	37
Dizzy Trout	1946	276	2.34	157	36
Denny McLain	1968	336	1.96	154	35
Justin Thompson	1997	223	3.02	152	34
Virgil Trucks	1949	275	2.81	148	32

Data source: Baseball-Reference.com 

The second and third spots belong to Newhouser  - a 195 ERA+ in 1945 and 190 in 1946.  Prince Hal appears two more times on the list for his 1942 and 1944 seasons.  Some historians have downplayed Newhouser's great seasons during the period because rosters were depleted by World War II from 1943-1945.  However, the rosters were at close to full strength for his outstanding 1942 and 1946 seasons.

Newhouser was not the only pitcher to have elite seasons in the 1940s.  In fact, nine of the top 15 seasons came during that decade.  That includes Dizzy Trout in 1944 and 1946, Bobo Newsome in 1940, Al Benton in 1945 and Virgil Trucks in 1949.

While the 1940s decade dominates the list, there have also been some remarkable seasons more recently.  Still very fresh on our minds is Verlander's amazing 2011 season where he compiled a 170 ERA+.  In an era where the Tigers had terrible teams and even worse pitching, Justin Thompson posted an impressive 152 ERA+ in 1997.  Mark Fidrych's 159 ERA+ in 1976 showed that he was much more than just a colorful character.

Some may be surprised that Denny McLain's 1968 season is ranked as low as #13.  There are a couple of reasons for that.  First, his 31 wins that year were partly a product of strong offensive support and his 1.86 ERA was only fourth best in the league.  Also, as mentioned in yesterday's post, ERA+ only measures the quality of a pitcher's season and does not give McLain credit for his 336 innings pitched.  Later, we'll discuss a metric which gives a pitcher credit for both quality and quantity.