Aledmys Diaz keeps hitting eighth

Obsessing over lineups is really easy to do. There is usually a new one every day, and given they come out several hours before the start of the game, scrutinizing lineups often helps pass the time until baseball actually starts. A recent obsession of mine and many Cardinals' fans is Aledmys Diaz's curious lineup positioning. Despite being the National League's best hitter (194 wRC+ is first) over a month into the season, Diaz cannot seem to shake the eighth spot in the lineup. It is a position that makes a lot of sense and no sense at the same time.

Aledmys Diaz has been amazing so far this year, and as Ben Markham noted in his recent piece, no Cardinals hitter has done more in one month to change his projections than the Cardinals current starting shortstop. After just 102 major league plate appearances, being older than many at his debut, and a minor league career that on the whole was more on the good than great side, DIaz has already upped his hitting projections to average with a .271/.314/.424 line and 101 wRC+.

While it might be nice to say that Mike Matheny should have put Diaz higher in the lineup a month ago and taken more advantage of his great production, the information we had at the time was little fuzzier as to how much of an impact he would have. As far as what the lineup should be going forward, we should be most concerned with expected production.

When it comes to a fairly standard Matheny-like lineup, we could use as follows:

One thing to notice is that this a deep lineup. The only "hole" is Kolten Wong and he is not too far from average and with base-running he is essentially average on offense. As far as lineups go based on these projections, this one is pretty good. Using the lineup tool here, this lineup scores 4.313 runs per game.

The lineup tool produces the best 30 lineups. A few notes from those lineups:

• The optimal lineup (Carpenter, Holliday, Diaz, Piscotty, Moss, Wong, Molina, Grichuk, Pitcher) scores 4.342 runs per game. Over the course of the season, the difference between the above lineup and the optimal lineup is less than five runs total. This is why, in the general scheme of things batting order does not matter much.
• Aledmys Diaz appears often at third, fifth, and eighth. We often think of the eighth place hitter as a poor hitter, but given how bad pitchers are at hitting generally, it is often incumbent on the eighth place hitter to do something big because if he fails, the pitcher is not likely to help. It is why Diaz, with a decent slugging percentage fits there, and why Randal Grichuk is basically the perfect eighth-place hitter.
• Matt Carpenter and Matt Holliday are very often the first two hitters with Stephen Piscotty the most common at cleanup. As the three best hitters in the lineup, this makes a lot of sense.