As a former College and Minor-League pitcher, I am going to have to mull this one over. It sounds good on paper but it isn't feasible. There is more to pitching than just going out and throwing a few innings then going out in a few days and do it again.
Pitchers on off days still throw a bullpen session to keep sharp, so the sheer # of pitches is still quite high. In no way, can I see this happen over 162 games, especially without expanding the rosters.
Then there is the issue of the staff aces, you can't just use them for a short stint and call in someone else. You want your best pitchers to see the most innings and there just isn't enough quality arms out there.
Interesting idea and I will dissect it further later but it just does not seem like a good idea.
I am very familiar with baseball and how it works, so I understand exactly how off days for pitchers are spent. That still doesn't have any impact on what I was saying.
Some teams are already doing this with their pitchers, they are just doing variations of it right now.
In the past, the game was different. Back then, pitchers tried to complete games and were only pulled out when it looked like the batters had caught up with their pitches. These days, most teams want 6 to 7 innings out of their starting pitchers except for a few elite pitchers who can be effective longer.
Again, look at the Dodgers. They had the second lowest team ERA in baseball this season behind the Astros. How many of their pitchers met the qualifications for awards, rankings, etc. stat wise? Not a single one because they usually only want their starting pitchers to get 5 or 6 innings.
There were a couple of other teams who started their bullpen pitchers with the intent they would only pitch one or two innings before the next pitcher would come in. While this may have been done in the past, it was done back then because of injuries to starting pitchers. Teams chose to do it this season when their starting pitchers were healthy.
Things are different now and the off-day schedules of pitchers will be altered and adapted to work with concept that I am predicting.
It is really all about statistical probabilities. Teams from 10+ years ago wanted their starting pitcher to win games for them. Now, metrics dictates you focus on outs, not games when it comes to your pitching staff.
I am not saying I like this change (because I do not), but from a pure strategical standpoint combined with statistical history, it is more efficient and logical to use your pitchers when they are at their best against batters. The Dodgers have been using a modified version of this by signing several starting pitchers to be bullpen pitchers, but they are not the only team doing this.
It's all about winning, not tradition. While no one is doing what I am predicting right now, I expect we will start to see it in the coming years.