Leftovers: A.J. Cole's time to prove himself as a big league starter may be running out

It's hard to draw much, if any, conclusion from just one spring training appearance, so it's completely unfair of me to pick on A.J. Cole in the manner I'm about to coming off his appearance on Saturday.

Cole gave up two earned runs on four hits in one inning, striking out one and allowing a long home run to Detroit Tigers catcher Bryan Holaday, who also homered off Stephen Strasburg earlier in the day.

Holaday, of course, has three big league home runs in 259 plate appearances over parts of four seasons.

Anyway, back to Cole.

The Washington Nationals major league depth for starters is perilously thin -- it's been one of my recurring themes if you've been reading my posts here. As of now, Tanner Roark and Joe Ross occupy the fourth and fifth slots. Behind them, and providing injury insurance, are 39-year-old Bronson Arroyo coming off surgery, phenom youngster Lucas Giolito, AAAA fodder Taylor Jordan and fading prospect Cole.

Cole, 25 in April, was the Nats' fourth round pick in the 2010 draft, traded to Oakland in the Gio Gonzalez deal in late 2011, and traded back to the Nats in the Michael Morse deal in early '13.

At several points in his minor league career, he was rated by Baseball America, Baseball Prospectus and MLB.com as one of the Top 100 prospects in the game, registering before last season at No. 30 by Baseball Prospectus, No. 52 by MLB.com and No. 91 by Baseball America.

After his 2015 season, when he compiled a stat line of 5-6, 3.15 ERA, 1.183 WHIP, 2.9 BB/9, 6.5 K/9 in 105.2 IP at AAA-Syracuse, he's been dropped off all three lists. Baseball America has him listed as the No. 66-ranked right-handed pitcher. (ed. note: Lucas Giolito is No. 1 on that list).

Plus, he got absolutely pounded in three big league appearances (11 runs and 14 hits in 9.1 IP) in his debut.

Cole fared better in Syracuse when he was sent back down. He gave up just two homers with a 1.89 ERA in 67 innings after June 24. He's a reincarnation of Dan Haren -- a guy who depends on a sinker to generate outs, with just enough stuff to generate enough Ks to keep hitters honest.

But his K rate has dropped with each advancement (9.5 in '13, 7.5 in '14, 6.5 in '15), which certainly doesn't bode well. It's one thing to keep the sinker down against double-A and triple-A hitters, it's another to do it to the big boys.

A lot of minor league starters with "big-league arms" -- and Cole qualifies -- get to be 24, 25, 26 and get transitioned into a reliever, pick up another tick or two on the fastball, and enjoy long careers. Joel Hanrahan, Tyler Clippard, Blake Treinen among many, many others all followed this route.

If Cole doesn't "make the jump" and isn't starting in the big leagues at some point this season, he may very well follow that path.