Indians pitchers are collectively striking out 9.29 batters per 9 innings, which would break the record for highest strikeout rate by any pitching staff in MLB history, a record currently held by... the 2014 Indians. The starting rotation is going its fair share of the striking out, with the same K/9 of 9.29 as the pitching stuff as a whole. They're on pace to break the starting rotation strikeout rate, which is also held by last year's Tribe.
Last week I wrote about the Tribe rotation becoming the first ever to have four pitchers reach 100+ strikeouts before the All-Star break. Trevor Bauer has been a very good strikeout pitcher this season, with a K/9 of 8.81, which ranks 8th in the American League. Danny Salazar (10.58), Corey Kluber (10.40), and Carlos Carrasco (10.14) have been a whole level above Bauer though, and that trio is on pace to do something that's never been done before.
Only 67 times in MLB history has a starting pitcher finished a full season with a K/9 of 10.00 or better. How many times has one team had three pitchers do it in the same season? Well, if you read my line in the last paragraphs about doing something that's never been done before, you already know the answer is "zero times."
No American League team has ever had even two such pitchers. (Mark Prior and Kerry Wood both did it for the 2003 Cubs; Randy Johnson and Curt Schilling both did it for the 2001 and 2002 Diamondbacks.) You can lower the bar quite a bit too, when you're talking about three pitchers all clearing the bar, because no team has ever had a trio of guys who each struck out 9+ per 9 innings for a full season.
If Salazar, Kluber, and Carrasco all reach 162 innings pitched this season, they're an awfully good bet to become the strikeoutingest trio of starters baseball has ever seen.