Why he's piquing the interest of fantasy owners:
He's given up three earned runs or less in each start since moving from the bullpen to the starting rotation. For being owned in only 4% of Yahoo leagues, his ERA & WHIP totals (2.86/0.99) are pretty enticing for people looking for an under the radar waiver wire bargain.
How I think he's going to do going forward:
While he has induced slightly more ground balls than last year (38% to 41%), I think his overall numbers will show modest improvement this year, I think the ERA ends up in the 3.75-4.00 range.
Like many unexpected players starting strong, he has been aided by some good luck (.215 BABIP and a 3.6% HR to FB ratio). He may keep this good stretch going for awhile but eventually hits are going to start falling and he's going to give up more home runs.
Whatever the results are, the fangraphs data indicates that he is at least making adjustments (which may help him do better than I expected). He has gone from using his fastball 61% of the time to 48% and increased the use of his cutter from 18% to 31% a pitch that seems to get him more effective results based on the available data.
Taking this under consideration is making me reconsider by initial prediction. I still think some regression is inevitable but he might be able to keep the ERA around the 3.50 range. If your playing fantasy, he may be useful if you have an extra bench spot available and would go on a start by start basis when determining whether or not to start him.
Also, if you are going to pick up/start Workman you may also need to keep an eye on whether he's playing at home or on the road as Fenway has been more favorable to offense this year (107 park factor) than usual.
Workman did get himself to the majors in decent time, as he was drafted in the second round of the 2010 draft. By career WAR, he is so far the fifth best player drafted in the second round of that year's draft with the best showing thus far coming from Andrelton Simmons.
The Red Sox themselves, while World Champions last year have not had the best of years so far as they are 31-36 and languishing in fourth place although the two ex-Brewers on the team (Burke Badenhop & Chris Capuano) are having solid seasons out of the bullpen.
All data numbers, etc. found on either baseball-reference.com or fangraphs.com