I made a brief and spirited Twitter argument the other day that Eddie Rosario could be — sooner, even, rather than later — a viable No. 3 hitter for the Twins. I think that in spite of his lack of plate discipline — just 15 walks as a rookie, to go with 118 strikeouts in 474 plate appearances, though that should improve some as he gets older

— he has the hands and the all-over-the-field power to be that good.

Some peg Rosario as a candidate for regression in 2016, arguing that his .332 batting average on balls in play last season (compared to a .267 overall mark) will naturally come down. That number to me isn't otherworldly, ranking just 39th in MLB among players with at least 450 plate appearances. It's far less troubling, for instance, than the .405 BABIP mark Danny Santana posted in 2014, leading the majors and indeed signaling a 2015 regression.

That said, while my argument for Rosario was born out of a confidence in him specifically, the impetus was the knowledge that the Twins, if you look at their projected, have nobody on their roster who is an ideal No. 3 hitter right now.

The Twins did, for several years, have a very good (and at times great) No. 3 hitter. And that hitter is still on the roster. His name is Joe Mauer.

In a pair of columns from spring training, Jim Souhan laid out both the lineup conundrum (concluding that things will get easier when and if Byron Buxton proves he can hit) and the Mauer conundrum (wondering if Mauer's problems of the past two years can be blamed on blurred vision due to concussions, as Joe has said, and concluding that coming clean about those problems and producing in 2016 would go a long way toward rehabbing his image with some fans).

Those two topics are related. Despite my assertion about Rosario in the No. 3 spot, Mauer's return to something that resembled his pre-2014 form would make the entire Twins' lineup a lot more sensible and strong.

Looking at Mauer between 2010 and 2013 — his first four seasons at Target Field, after he had already won his three batting titles and MVP award — you still find an incredibly adept No. 3 hitter. His OPS in three of those four seasons was between .861 and .880, with the outlier being the wasted "bilateral leg weakness" year of 2011 when he wasn't healthy.

Last year's Twins had Miguel Sano post a .916 OPS with major home run power. He's the clear cut cleanup hitter. They had SEVEN other regulars, including Mauer, who had an OPS between .702 and .754 — basically a whole bunch of average interchangeable parts (the average OPS in the AL last season was .730).

What we don't know is this: 1) Did Mauer's numbers decline the past two years because of vision problems, age (he'll be 33 soon) or some combination of both. 2) If it was more driven by vision problems, have those problems been corrected to a degree that will allow him to return to a much higher level of production than he showed the past two years (when his OPS was .732 and .718, respectively).

I'm inclined to think on the first point that concussions/vision problems were certainly the largest factor, by a wide margin. Vision is so important to any hitter — especially a precise hitter like Mauer — and the dropoff was steeper than one would naturally expect due to age.

The second point? That's the great unknown and, really, the one that could be the deciding factor between a decent Twins lineup this year and one that is decidedly above-average.