Oakland A's shortstop Marcus Semien is having the breakout season we hoped for in 2016

Since as far back as the second half of last season, we here at Athletics Nation have identified Marcus Semien as a breakout candidate for 2015. We mentioned it as far back as mid-September, then again in November, and January, and during spring training in March. None of that is to say this was a particularly bold pick, and in fact it was a pretty obvious call, but the point is that the concept of Semien having a breakout this year is extremely well-established.

Why was Semien's breakout such an easy prediction to make? Consider what he did last year. In the field he was atrocious, but as the summer went on he made arguably the biggest, most visible in-season defensive improvements I've ever seen from a player. In April he looked like he'd never played the position before, and by September he looked downright average. At the plate, he hit better than most shortstops but still finished with an OPS+ of 96 and a wRC+ of 98. All told, he was below-average on both sides of the ball.

Ah, but there was context. We already knew this spring, or at least safely assumed, that his below-average defense had been fixed and would not be as much of a problem in the future. And entering his age-25 season, still inching toward his prime rather than passing it, there was every reason to expect improvement at the plate from a guy who had generally hit well in the minors. He managed to be around a 2-WAR player in 2015 despite his shortcomings, but the signs pointed toward a guy who could potentially be an above-average hitter while playing at least average defense at shortstop. That's the description of a 4-WAR player and a likely All-Star at a relatively thin position. Hence, our excitement here on AN.

Well, here we are in mid-May, and I am happy to report that it's all coming true. And it could still get even better.

Defense

The defensive side of things has been widely reported and you're probably sick of hearing about it by now, but really stop and think about it. Semien has made two errors so far in 39 games. Last year, through 39 games, he'd made 14 errors. And he made his 15th the next day. The current MLB leader in 2016 (at any position) is Aledmys Diaz of the Cardinals, with nine. It's difficult to remember just how bad Semien was at this point last year. It's even more amazing how good he's been just 12 months later.

Granted, errors are a dumb way to measure defense, but it's worth noting that the eyeball test completely backs up the talk of his improvement. Semien is displaying more range and a more accurate arm, both thanks largely to improved footwork. His hands are more sure and he doesn't clank the ball off of his glove, likely due to all the extra work he does with Ron Washington and the flat glove on the practice field. He even looks like a natural when he turns the double play. Here's an excellent play that Semien absolutely would not have made last year:

Last year, there is no question that ball would have gotten past him. He probably wouldn't even have gotten a glove on it. And even if he had somehow come up with it, he would have freaked out and rushed the throw and ended up winging the ball into the stands. Note that the runner there was Adam Jones, a Gold Glove center fielder with five seasons of double-digit steals. Semien didn't have a whole lot of time there. Here's another play:

That bad hop would have eaten him up last year. And a perfect spin throw to first? Fuhgeddaboutit. I don't want to load this up with too many videos, but here's another great play ranging out to catch a popup Mays-style, another one snaring a rocket on the outfield grass to throw out the speedy Jackie Bradley, and another rocket snare while playing out of position during a shift. And all of those plays are from May. I didn't even have to go back to April for this.

When it comes to hitting, hot streaks come and go. Pitchers adjust to you, you adjust back, etc. But you can either play defense or you can't, for the most part. Improvement only comes after countless hours of practice, if at all, and decline usually only comes due to age or injury or being named Chuck Knoblauch or Steve Sax. Semien has now learned to play defense, with his skills catching up to his physical ability. He is a legit shortstop, and the only question is if he's merely average or pushing the boundaries of above-average.

Offense

At every stop of the minors, from High-A to Double-A to Triple-A, Semien displayed power and patience. He would hit for a decent average, but his walk rates were huge and he knocked around 15 homers per year with isolated slugging marks of .193 and up. Here's how he's done in his two seasons with the A's:

First, the plate discipline. The strikeout rate is probably real, since despite being a patient hitter who sees more pitches per plate appearance than anyone else on the team, he still swings and misses a lot. His strikeout rate is in that range where it's slightly higher than you'd like but it's not really a problem on its own, and I figure it will remain there. His walk rate, though, has spiked up to the level you might hope for based on his minor league track record. In fact, it's the highest on the team.

And what about that power? He's tied with David Ortiz for fifth in the entire AL in homers, and he's already two-thirds of the way to last year's total in about a quarter of the at-bats. I was hoping for 20-homer power, but maybe he can do even better than that. His profile page on ESPN projects him to reach 42 long balls, and I virtually guarantee he won't keep that pace, but is it crazy to raise our hopes to the neighborhood of 25-30? From an everyday shortstop with good defense?

Now, I do find it strange that he has only one double to go along with those 10 homers, and that kind of oddity makes me wonder if he's hitting lots of cheap homers into the first row of seats which will eventually stop clearing fences when his luck runs out. However, Hit Tracker Online says that is not the case -- seven of his dingers were ranked as either "Plenty" or "No Doubters" and would have gone out in all 30 parks, two were "Just Enough" and would only have gone out in a majority of parks, and only one was truly lucky. When Semien gets all of it, it goes out, no questions asked.

Here's the best part. In the intro I mentioned the chance for further improvement, and that's due to Semien's .220 batting average. However, that mark comes with a .207 BABIP, which is down from his career mark of .302. On one hand, it's lazy to just look at a weird BABIP and assume it'll correct itself, but sometimes the number is extreme enough to warrant such analysis. Semien is simply not going to finish the year with that .207 mark; it will go up, because he is a professional hitter with good footspeed who isn't being overwhelmed by his competition. Only five full-time hitters finished below .250 last year, and three of them were at least 35 years old.

You could point to Semien's wonky batted ball profile, which is high on grounders and low on liners, but that's kind of the point of this small-sample caveat -- those rates will even out in time as well, which is one reason the BABIP will improve. Perhaps that's what will slow down his HR rate, with some of those hard-hit flies being replaced with hard-hit liners (resulting in those currently absent doubles), but one way or other a few extra outs will turn into hits. I'm not expecting anything more than a .250 average, not with all the homers and strikeouts he racks up, but even that would be enough to put his OPS well above .800; only 39 qualified hitters last year managed a mark of .820 or higher.

***

In 2015, Marcus Semien was a decent player, but he was a below-average defensive shortstop and a below-average hitter. This year, he has improved dramatically on both sides of the ball, becoming at least an average defender and an above-average hitter with room for improvement. Grabbing an All-Star berth will be tough now that Manny Machado has moved back to SS, with big names like Bogaerts, Correa, Lindor, and Tulowitzki all in the picture as well, but that's just details. Other than his fluky-low batting average, Semien is having exactly the breakout season we all hoped for, if not better. Addison Who?