Recent readers of the Box may be aware of my crusade against the 8-man bullpen. I have nothing against it in principle, except that until September, the active roster for major league teams is limited to 25 players. When rosters expand, if you want a 14-man bullpen, I will raise a figurative glass of ale and say, why the heck not!
I'll add another caveat. On teams with weak starting pitchers wherein several starting pitchers have difficulty reaching the 6th and 7th innings, a three-man bench is defensible as long as at least two players and/or one regular are reasonably versatile. I don't believe the current Jays are in that category.
I define position player versatility as follows: 1) ability to play multiple defensive positions adequately; 2) speed for the purposes of running the bases; 3) ability to hit right and left handed pitching well/switch-hitting ability; 4) above average defensive ability at at least one position.
Let's look at the current best lineup the Jays feature: Tulowitzki SS, Donaldson 3B, Bautista RF, Encarnacion DH, Smoak 1B, Martin C, Goins 2B, Pillar CF, Revere LF. This is the lineup that the Jays set on Friday against the Yankees. Five of those players (the first four plus Martin) are stars and you would never take them out of a game, except due to injury or for rest purposes. I would add Smoak to that list because he is a switch-hitter and by far the best defensive first baseman on the team, and it is usually counterproductive to downgrade your defense in the late innings. That leaves three players that could be subject to a tactical substitution.
Of course, the purpose of a bench is not limited to in-game tactics. Giving your players the occasional day off is almost universally regarded as a good idea in order to keep them fresh. This is especially true later in the season in the hot weather months. Very few players play 155 games or more without ever taking a few innings off and that is because (a) they sustain nagging injuries that require rest and (b) managers realize that even extremely durable players perform better when they get a day or even a few innings off even when healthy.
A good bench should have players capable of handling each defensive position competently and with something not too far below league average hitting ability for the position (e.g. you don't want Kawasaki as your backup first baseman).
OUR TWO-MAN BENCH
Two? Yes. When the Blue Jays start their A lineup, they back it up with a two-man bench. For all practical purposes Dioner Navarro is not part of the position player bench when Russell Martin starts the game. Navarro is not a good enough hitter or baserunner to productively sub in for Martin. And Navarro will rarely if ever pinch hit for anyone else either - if he did he would have to be replaced defensively and thus the Jays would lose their backup catcher and insurance in case Martin needs to come out due to injury. But there is the DH spot, where Navarro could hit and remain in the game, except that he is not going to pinch hit for Edwin Encarnacion either. In this scenario, Navarro's role is limited to subbing in for Martin or for Encarnacion in case of a blowout or injury. He has no pinch hitting tactical value in that role.
Bench player #1 is Chris Colabello. Colabello has had an excellent year hitting and can hit both lefties and righties well. He is a defensive liability at first base and outfield and is a below average runner. In recent weeks, he has been (all but) removed from his role as part-time first baseman due to substandard defense.
Bench player #2 is Cliff Pennington. The veteran acquired from Arizona, believed to be an upgrade over Kawasaki as the utility infielder. Pennington has a solid defensive reputation - however, his batting skills can only be considered adequate for a second baseman or shortstop, and substandard for a third baseman. He is not particularly fast.
To sum up, you have one player with very good pinch hitting utility, one player with good infield defensive utility, and one player with marginal baserunning utility. And that is it. There is no one with above average baserunning skill and no one with defensive outfield utility.
Both players were used in the 9th inning on Friday and the lack of versatility showed as Bench Player #2 had to sub in for Bench Player #1. The Jays burned both their bench players on one lineup spot. Limited bench versatility leads to limited deployment options, which results in opposing managers having an easier time dealing with uncertainties in the latter innings of close games. This is an important tactical point: if your opponent isn't sure what you are going to do, he will have to make his preparations based on best guesses and sometimes those guesses will be wrong. That opens the door to being tactically outmaneuvered.
WHO NEEDS DAYS OFF
The open sore on the current roster construction is the lack of a 4th outfielder, as evidenced by the team's unwillingness to put Colabello out there. A contending team playing through two weeks of baseball without a 4th outfielder on the roster must be exceedingly rare - I can't recall it ever happening before. The minor injury to Encarnacion was an opportunity to give Jose Bautista some rest time at DH, but of course this was not possible. Kevin Pillar has also looked like he needed some time off: he had an uncharacteristically poor defensive game on Thursday against the Athletics and has not hit well in recent weeks. The usual medicine for this situation is to give them a day off or two from running around the outfield.
MY IDEAL ROSTER COMPOSITION
In cases wherein the starting pitchers can be counted on to reach the 6th and 7th innings with regularity, my ideal roster construction is 14 position players and 13 pitchers (with two of them in AAA). Relief pitchers can be recalled from AAA easily if an unusual situation develops causing you to use up too many of your relief pitchers at once, such as a long extra-inning game. I want the position player bench to be versatile: to have one or two players who can hit righties, one or two players who can hit lefties, at least one player with loads of speed, and a couple of guys with defensive ability.
14 position players implies a 5-man bench. Here are the types of players I'd like to see on a bench:
1) The second catcher, used to give the primary catcher at least one day off per week.
2) 4th outfielder with high defensive utility, preferably with pinch hitting and speed value. Could be part of a productive outfield platoon.
3) Utility infielder, with at least good defense at multiple positions, some speed and a decent bat against either lefties or righties
4) A hitter with pinch hitting utility, preferably bats left if your lineup is righty heavy and right if it is lefty heavy. Defensive value and speed is a bonus. Can function as 5th outfielder or platoon first baseman.
5) Choice of...
(a) Third catcher, so that your number two catcher can be used more widely as a pinch hitter.
(b) A very fast baserunner, capable of going first to third on most singles and occasionally stealing a base.
(c) A second utility infielder, preferably hitting left if your first utility infielder hits right, or vice-versa.