It's going to be a small class, and we know that, because there are not a lot of Seniors leaving. Therefore we won't see an across the board group that covers all positions. Instead this class needs to be spotty, and fill positions of need. I took a look at the current players, and projected what I think are the positions of need for the 2015 class:

Offense
QB (1) Every class should have a QB in it
RB (1) This one is done now
WR (1) Ohio really stocked up on some great WRs last year, but at least one in a class is good
TE  (0) They could take one, but it isn't essential, if Henry, Mason, Morgan, and Brown are healthy.
OL (2) They stocked up last year. Two is probably enough, given the small class
PK (0) With Royster coming in, should be fine for years to come

Defense
DT (2-4) This is the one position that I see wiith a critical need. After any recruits redshirt in 2015, only Porter and Aloese will be left.They many have to move one of the DE's inside, perhaps Kuhar, and they may have to take a JUCO or two.
DE (1) Not an urgent need, but one in a class is good to have
LB (2)  Two seems like a good number
DB (1) There should be at least one per class
LS (1) Taken care of
P (1) Venham and Bonnstetter will be Juniors this year, so it's time to start looking for one, this year or next.

That's about 14, which is about as big as I see this class getting.

I'm not talking about 2014, nor 2015. Ohio will be very deep at DT this fall, and as you said, there will be still be good depth in 2015  2016, however, is a different situation. Over the next two years you will lose Crutcher, McLeod, Purdum, and Tautuaiki, leaving only Porter and Aloese.  The walkon/grayshirt Chalmer Freuauf may also figure into the picture as well.

If you recruit someone in the 2015 class, particularly for a line position, you expect them to redshirt in 2015, and to fight for a playing role in 2016 as a redshirt Freshman, but then to be a major contributor in 2017-2019. If you want to have players ready for 2016 and beyond, they either need to be recruited now, or you will need to add JUCOs later, or move someone inside such as Sayles or Kuhar.

With 7 recruits in, this is my remaining shopping list:
QB (1)
WR (1)
DT (2)
DB (1)
P (0-1)

which would be a total of 13. If more than that are awarded, they should go to the best available athlete.

Definitely need a few more DBs now, having lost Stewart and (probably) Washington.

To show how I come to my numbers, I look at 2 years out, which would be 2016. By then the juniors and seniors on this year's team will be gone, and the class of 2015 will have had a chance to redshirt, and be available to play, but mostly the class of 2016 will be redshirting that year. Thus you will have ~65 scholarship players available to play, which will include the current true freshmen, redshirt freshmen, and sophomores, plus the players being recruited this year. Here is how I see it:

      Ideal  Soph   Rd-Fr  Tr Fr  Gryshrt  2015   Total Still Need
QB      4      2      0      1       0       1      4       0
RB      4      0      1      2       0       1      4       0
FB      0      0      0      0       0       0      0       0
WR      8      4      3      3       0       1     11      -3
TE      5      2      1      1       0       0      4       1
OL     13      3      1      5       0       2     11       2
DT      6      0      2      0       1       1      4       2
DE      6      3      1      2       0       1      7      -1
OLB     6      2      3      0       0       1      6       0
ILB     3      1      0      1       0       1      3       0
CB      6      0      1      3       0       0      4       2
S       5      2      2      0       0       1      5       0
P       1      0      0      0       0       0      0       1
K       1      0      0      0       1       0      1       0
LS      1      0      0      0       0       1      1       0
Tot    69     19     15     18       2      11     65

Normally I'd like to see 3-deep at each position. For some skill positions, like QB and RB, I'd like to see 4.  For other positions, where walkons often play, like OL and Safety, a bit under 3. There is some flexibility, obviously. If you are low at a position, it increases the chance that you will play a true freshman from the class of 2016 at that position, or that you would recruit a JUCO in 2016 is bolster that position.

The players I included at Greyshirts are Royster and Freuaf.  Note that there are some walkons currently listed on the 2-deep who are also underclassmen,  Zach Adams OL R-Fr, and  Cody Grillot MLB R-Fr, so they would reduce the need at those positions.

In the end that leaves me with the current needs of a punter, 2 defensive backs, 2 defensive tackles, plus possibly another offensive lineman and TE. Recruiting a punter in 2016, or doing walkon tryouts for a punter in 2016 also could work.