When a straight line is drawn from the point of ground to the point of the deck, you can see the slide is quite steep. Often you can find plywood scraps on Craigslist of Freecycle for very little, or free. Personally, I'd get some plywood scrap and attach it to the slides to even out the slope, as the red line shows. You should be able to put plywood on here for next to no cost.
RATCHX3 High Jinks vom Neuanfang - Gotchya Day: 1/23/2013 DN, SG, SR, CA
Inspire Spark to Ignition! (Ignite) Gotchya Day: 10/8/2016
C-ATCH Pimg - RATO, UJJ (x2), DJX, HIT, CA, CGC, High in Games, Reserve High in Standard- CPE Nationals 2014